Change actions to python2_actions as needed.

As a prelude to starting to move the build fully over to
Python 3, this CL changes all of the GN `action` and
`action_foreach` targets that appear to require Python 2
over to `python2_action` and `python2_action_foreach`.

This CL by itself should produce no functional change since
we'll still be using Python 2 by default, and the new templates
are passthroughs in that config.

To start using Python3, you can run
`gn gen --script-executable=python3 //out/Default` on Unix; on
Python3 you need to point to an actual python3.exe and not
the python3.bat wrapper in depot_tools; once we can roll GN forward
to a version that contains
https://gn-review.googlesource.com/c/gn/+/10560 (which will hopefully
happen in the next day or two), that won't be necessary.

The Fuchsia build will not work until http://fxrev.dev/446479 lands
and is rolled in.

No-Presubmit: true
Bug: 1112471
AX-Relnotes: n/a
Change-Id: I891155502e0940a8075cf26d675f54b803d91242
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2510878
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Bruce Dawson <brucedawson@chromium.org>
Reviewed-by: Mark Mentovai <mark@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Commit-Queue: Dirk Pranke <dpranke@google.com>
Cr-Commit-Position: refs/heads/master@{#824216}

ash/BUILD.gn

@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 
 import("//build/config/features.gni")
+import("//build/config/python.gni")
 import("//build/config/ui.gni")
 import("//chromeos/assistant/ambient.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
@@ -1888,7 +1889,8 @@ component("ash") {
   }
 }
 
-action("dbus_service_files") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("dbus_service_files") {
   sources = [
     "dbus/org.chromium.DisplayService.conf",
     "dbus/org.chromium.GesturePropertiesService.conf",

build/config/android/copy_ex.gni

@@ -23,6 +23,9 @@ import("//build/config/python.gni")
 
 template("copy_ex") {
   action_with_pydeps(target_name) {
+    # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+    run_under_python2 = true
+
     forward_variables_from(invoker,
                            [
                              "data",

build/config/android/internal_rules.gni

@@ -180,6 +180,9 @@ template("write_build_config") {
   }
 
   action_with_pydeps(target_name) {
+    # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+    run_under_python2 = true
+
     forward_variables_from(invoker,
                            [
                              "deps",
@@ -633,6 +636,9 @@ template("generate_android_wrapper") {
 
 template("generate_r_java") {
   action_with_pydeps(target_name) {
+    # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+    run_under_python2 = true
+
     forward_variables_from(invoker,
                            [
                              "deps",
@@ -986,6 +992,9 @@ template("test_runner_script") {
 if (enable_java_templates) {
   template("android_lint") {
     action_with_pydeps(target_name) {
+      # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+      run_under_python2 = true
+
       forward_variables_from(invoker, [ "testonly" ])
       if (!defined(deps)) {
         deps = []
@@ -1291,6 +1300,9 @@ if (enable_java_templates) {
       _expectations_target =
           "${invoker.top_target_name}_validate_proguard_config"
       action_with_pydeps(_expectations_target) {
+        # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+        run_under_python2 = true
+
         script = _script
 
         # Need to depend on all deps so that proguard.txt within .aar files get
@@ -1334,6 +1346,9 @@ if (enable_java_templates) {
       _deps += [ ":$_expectations_target" ]
     }
     action_with_pydeps(target_name) {
+      # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+      run_under_python2 = true
+
       script = _script
       deps = _deps
       inputs = _inputs
@@ -1363,6 +1378,9 @@ if (enable_java_templates) {
   #
   template("java_binary_script") {
     action_with_pydeps(target_name) {
+      # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+      run_under_python2 = true
+
       forward_variables_from(invoker,
                              [
                                "deps",
@@ -1569,6 +1587,9 @@ if (enable_java_templates) {
         _main_dex_list_path = invoker.output + ".main_dex_list"
         _main_dex_list_target_name = "${target_name}__main_dex_list"
         action_with_pydeps(_main_dex_list_target_name) {
+          # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+          run_under_python2 = true
+
           forward_variables_from(invoker, [ "testonly" ])
 
           script = "//build/android/gyp/main_dex_list.py"
@@ -1643,6 +1664,9 @@ if (enable_java_templates) {
       }
 
       action_with_pydeps(target_name) {
+        # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+        run_under_python2 = true
+
         forward_variables_from(invoker,
                                [
                                  "data",
@@ -2220,6 +2244,9 @@ if (enable_java_templates) {
   #
   template("prepare_resources") {
     action_with_pydeps(target_name) {
+      # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+      run_under_python2 = true
+
       forward_variables_from(invoker,
                              [
                                "deps",
@@ -2711,6 +2738,9 @@ if (enable_java_templates) {
       _expectations_target =
           "${invoker.top_target_name}_validate_android_manifest"
       action_with_pydeps(_expectations_target) {
+        # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+        run_under_python2 = true
+
         _actual_file = "${invoker.android_manifest}.normalized"
         _failure_file =
             "$_expectations_failure_dir/" +
@@ -2753,6 +2783,9 @@ if (enable_java_templates) {
     }
 
     action_with_pydeps(target_name) {
+      # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+      run_under_python2 = true
+
       script = _script
       depfile = "$target_gen_dir/${target_name}.d"
       inputs = _inputs
@@ -2775,6 +2808,9 @@ if (enable_java_templates) {
   #
   template("create_size_info_files") {
     action_with_pydeps(target_name) {
+      # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+      run_under_python2 = true
+
       forward_variables_from(invoker,
                              [
                                "testonly",
@@ -2996,6 +3032,8 @@ if (enable_java_templates) {
       _expectations_target =
           "${invoker.top_target_name}_validate_libs_and_assets"
       action_with_pydeps(_expectations_target) {
+        # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+        run_under_python2 = true
         _actual_file = "$target_gen_dir/$target_name.libs_and_assets"
         _failure_file =
             "$_expectations_failure_dir/" +
@@ -3033,6 +3071,8 @@ if (enable_java_templates) {
       _deps += [ ":$_expectations_target" ]
     }
     action_with_pydeps(target_name) {
+      # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+      run_under_python2 = true
       depfile = "$target_gen_dir/$target_name.d"
       inputs = _inputs
       deps = _deps
@@ -3139,6 +3179,9 @@ if (enable_java_templates) {
     }
 
     action_with_pydeps(target_name) {
+      # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+      run_under_python2 = true
+
       if (invoker.use_turbine) {
         script = "//build/android/gyp/turbine.py"
       } else {
@@ -4267,6 +4310,8 @@ template("create_android_app_bundle_module") {
   if (defined(invoker.expected_libs_and_assets)) {
     _expectations_target = "${invoker.top_target_name}_validate_libs_and_assets"
     action_with_pydeps(_expectations_target) {
+      # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+      run_under_python2 = true
       _actual_file = "$target_gen_dir/$target_name.libs_and_assets"
       _failure_file = "$_expectations_failure_dir/" +
                       string_replace(invoker.expected_libs_and_assets, "/", "_")
@@ -4312,6 +4357,8 @@ template("create_android_app_bundle_module") {
   }
 
   action_with_pydeps(target_name) {
+    # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+    run_under_python2 = true
     deps = _deps
     inputs = _inputs
     outputs = _outputs

build/config/android/linker_version_script.gni

@@ -16,6 +16,9 @@ import("//build/config/python.gni")
 #
 template("generate_linker_version_script") {
   action_with_pydeps(target_name) {
+    # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+    run_under_python2 = true
+
     script = "//build/android/gyp/generate_linker_version_script.py"
     outputs = [ invoker.linker_script ]
     inputs = []

build/config/android/rules.gni

@@ -659,6 +659,9 @@ if (enable_java_templates) {
   #   }
   template("jinja_template") {
     action_with_pydeps(target_name) {
+      # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+      run_under_python2 = true
+
       forward_variables_from(invoker,
                              [
                                "visibility",
@@ -862,6 +865,9 @@ if (enable_java_templates) {
     _generating_target_name = "${target_name}__template"
 
     action_with_pydeps(_generating_target_name) {
+      # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+      run_under_python2 = true
+
       forward_variables_from(invoker,
                              [
                                "deps",
@@ -3302,6 +3308,9 @@ if (enable_java_templates) {
       }
       _apk_operations_target_name = "${target_name}__apk_operations"
       action_with_pydeps(_apk_operations_target_name) {
+        # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+        run_under_python2 = true
+
         _generated_script = "$root_build_dir/bin/${invoker.target_name}"
         script = "//build/android/gyp/create_apk_operations_script.py"
         outputs = [ _generated_script ]
@@ -4222,6 +4231,9 @@ if (enable_java_templates) {
     assert(_scanned_files.has_classes_jar || _scanned_files.subjars == [])
 
     action_with_pydeps(_unpack_target_name) {
+      # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+      run_under_python2 = true
+
       script = "//build/android/gyp/aar.py"  # Unzips the AAR
       args = [
         "extract",
@@ -4873,6 +4885,9 @@ if (enable_java_templates) {
 
     _bundle_target_name = "${_target_name}__bundle"
     action_with_pydeps(_bundle_target_name) {
+      # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+      run_under_python2 = true
+
       script = "//build/android/gyp/create_app_bundle.py"
       inputs = _all_module_zip_paths + _all_module_build_configs
       outputs = [ _bundle_path ]
@@ -4972,6 +4987,9 @@ if (enable_java_templates) {
     _bundle_wrapper_script_path = "$_bundle_wrapper_script_dir/$_target_name"
 
     action_with_pydeps("${_target_name}__wrapper_script") {
+      # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+      run_under_python2 = true
+
       script = "//build/android/gyp/create_bundle_wrapper_script.py"
       inputs = [ _base_module_build_config ]
       outputs = [ _bundle_wrapper_script_path ]

build/config/chromeos/rules.gni

@@ -5,6 +5,7 @@
 import("//build/config/chrome_build.gni")
 import("//build/config/chromeos/args.gni")
 import("//build/config/gclient_args.gni")
+import("//build/config/python.gni")
 
 assert(is_chromeos)
 
@@ -97,7 +98,8 @@ template("generate_runner_script") {
          "Tast tests are invoked from binaries shipped with the VM image. " +
              "There should be no locally built binary needed.")
 
-  action(target_name) {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action(target_name) {
     if (defined(runtime_deps_file)) {
       write_runtime_deps = runtime_deps_file
     }

build/config/nacl/rules.gni

@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 
 import("//build/config/nacl/config.gni")
+import("//build/config/python.gni")
 
 # Generate a nmf file
 #
@@ -19,7 +20,8 @@ template("generate_nmf") {
   assert(defined(invoker.executables), "Must define executables")
   assert(defined(invoker.nmf), "Must define nmf")
 
-  action(target_name) {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action(target_name) {
     forward_variables_from(invoker,
                            [
                              "deps",

build/config/python.gni

@@ -63,6 +63,8 @@ template("python_library") {
   }
 }
 
+_is_python2 = exec_script("//build/util/is_python2.py", [], "json")
+
 # This is a wrapper around action() that ensures that the script is
 # run under a Python2 executable, even if the main script_executable is
 # Python3.
@@ -86,28 +88,32 @@ template("python2_action") {
     forward_variables_from(invoker,
                            "*",
                            [
-                             "script",
-                             "inputs",
-                             "args",
                              "testonly",
                              "visibility",
                            ])
 
-    script = "//build/util/python2_action.py"
-    if (!defined(invoker.inputs)) {
+    if (!_is_python2) {
+      script = "//build/util/python2_action.py"
+      _rebased_script = rebase_path(invoker.script, root_build_dir)
+      inputs = []
       inputs = [ invoker.script ]
-    } else {
-      inputs = [ invoker.script ] + invoker.inputs
+      if (defined(invoker.inputs)) {
+        inputs += invoker.inputs
+      }
+      args = []
+      args = [ _rebased_script ]
+      if (defined(invoker.args)) {
+        args += invoker.args
+      }
     }
-    args = [ rebase_path(invoker.script, root_build_dir) ] + invoker.args
   }
 }
 
-# This is a wrapper around action() that ensures that the script is
+# This is a wrapper around action_foreach() that ensures that the script is
 # run under a Python2 executable, even if the main script_executable is
 # Python3.
 #
-# It supports all of action()'s arguments.
+# It supports all of action_foreach()'s arguments.
 #
 # TODO(crbug.com/1112471): Remove this once everything runs cleanly under
 # Python3.
@@ -126,20 +132,24 @@ template("python2_action_foreach") {
     forward_variables_from(invoker,
                            "*",
                            [
-                             "script",
-                             "inputs",
-                             "args",
                              "testonly",
                              "visibility",
                            ])
 
-    script = "//build/util/python2_action.py"
-    if (!defined(invoker.inputs)) {
+    if (!_is_python2) {
+      script = "//build/util/python2_action.py"
+      _rebased_script = rebase_path(invoker.script, root_build_dir)
+      inputs = []
       inputs = [ invoker.script ]
-    } else {
-      inputs = [ invoker.script ] + invoker.inputs
+      if (defined(invoker.inputs)) {
+        inputs += invoker.inputs
+      }
+      args = []
+      args = [ _rebased_script ]
+      if (defined(invoker.args)) {
+        args += invoker.args
+      }
     }
-    args = [ rebase_path(invoker.script, root_build_dir) ] + invoker.args
   }
 }
 
@@ -197,7 +207,7 @@ template("action_with_pydeps") {
     _script_dir = get_path_info(_pydeps_file, "dir")
     inputs += rebase_path(_pydeps_entries, ".", _script_dir)
 
-    if (defined(run_under_python2) && run_under_python2) {
+    if (defined(run_under_python2) && run_under_python2 && !_is_python2) {
       inputs += [ invoker.script ]
       _args = args
       args = []
@@ -246,7 +256,7 @@ template("action_foreach_with_pydeps") {
     _script_dir = get_path_info(script, "dir")
     inputs += rebase_path(_pydeps_entries, ".", _script_dir)
 
-    if (defined(run_under_python2) && run_under_python2) {
+    if (defined(run_under_python2) && run_under_python2 && !_is_python2) {
       inputs += [ invoker.script ]
       _args = args
       args = []

build/dotfile_settings.gni

@@ -25,6 +25,7 @@ build_dotfile_settings = {
     "//build/config/mac/mac_sdk.gni",
     "//build/config/mac/rules.gni",
     "//build/config/posix/BUILD.gn",
+    "//build/config/python.gni",
     "//build/config/sysroot.gni",
     "//build/config/win/BUILD.gn",
     "//build/config/win/visual_studio_version.gni",

build/nocompile.gni

@@ -59,6 +59,7 @@
 # least processed when things go right.
 
 import("//build/config/clang/clang.gni")
+import("//build/config/python.gni")
 import("//build/toolchain/toolchain.gni")
 import("//testing/test.gni")
 
@@ -74,7 +75,8 @@ if (enable_nocompile_tests) {
   template("nocompile_test") {
     nocompile_target = target_name + "_run_nocompile"
 
-    action_foreach(nocompile_target) {
+    # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+    python2_action_foreach(nocompile_target) {
       testonly = true
       script = "//tools/nocompile_driver.py"
       sources = invoker.sources

build/toolchain/win/midl.gni

@@ -89,7 +89,7 @@ template("midl") {
   proxy_file = "{{source_name_part}}_p.c"
   type_library_file = "{{source_name_part}}.tlb"
 
-  # TODO(crbug.com/1112471): Get this working directly under Python 3.
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
   python2_action_foreach(action_name) {
     visibility = [ ":$source_set_name" ]
     script = "//build/toolchain/win/midl.py"

build/util/is_python2.py

@@ -0,0 +1,9 @@
+# Copyright 2020 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+"""Script for checking if we're running Python 2 or 3."""
+
+import subprocess
+import sys
+
+print("true" if sys.version_info.major == 2 else "false")

chrome/BUILD.gn

@@ -7,6 +7,7 @@ import("//build/config/chromeos/ui_mode.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/features.gni")
 import("//build/config/locales.gni")
+import("//build/config/python.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 import("//build/config/ui.gni")
 import("//build/config/win/console_app.gni")
@@ -59,7 +60,8 @@ if (enable_resource_allowlist_generation) {
 }
 
 if (is_win) {
-  action("reorder_imports") {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action("reorder_imports") {
     script = "//build/win/reorder-imports.py"
 
     # See comment in chrome_dll.gypi in the hardlink_to_output

chrome/android/BUILD.gn

@@ -685,7 +685,8 @@ group("jni_headers") {
   ]
 }
 
-action("chrome_android_java_google_api_keys_srcjar") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("chrome_android_java_google_api_keys_srcjar") {
   script = "//build/android/gyp/java_google_api_keys.py"
   _output_path = "$target_gen_dir/$target_name.srcjar"
   outputs = [ _output_path ]

chrome/android/features/android_library_factory_tmpl.gni

@@ -73,6 +73,9 @@ template("android_library_factory") {
   _base_gen_dir = "${target_gen_dir}/${target_name}"
 
   action_foreach_with_pydeps(_process_factory_target_name) {
+    # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+    run_under_python2 = true
+
     script = "//chrome/android/features/create_stripped_java_factory.py"
     sources = invoker.sources
     outputs =

chrome/android/webapk/shell_apk/mustache_pass.gni

@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 
 import("//build/config/android/rules.gni")
+import("//build/config/python.gni")
 
 template("mustache_pass") {
   forward_variables_from(invoker, [ "testonly" ])
@@ -10,7 +11,8 @@ template("mustache_pass") {
   assert(defined(invoker.input))
   assert(defined(invoker.output))
 
-  action(target_name) {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action(target_name) {
     forward_variables_from(invoker,
                            [
                              "visibility",

chrome/app/BUILD.gn

@@ -64,6 +64,9 @@ if (is_android) {
 }
 
 grit("generated_resources") {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  run_under_python2 = true
+
   source = "generated_resources.grd"
   defines = chrome_grit_defines
   output_dir = "$root_gen_dir/chrome"

chrome/browser/BUILD.gn

@@ -6278,6 +6278,9 @@ proto_library("permissions_proto") {
 }
 
 grit("resources") {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  run_under_python2 = true
+
   source = "browser_resources.grd"
 
   # Required due to flattenhtml = "true" on a generated file.

chrome/browser/chromeos/BUILD.gn

@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 
 import("//build/config/features.gni")
+import("//build/config/python.gni")
 import("//build/config/ui.gni")
 import("//chromeos/components/chromebox_for_meetings/buildflags/buildflags.gni")
 import("//extensions/buildflags/buildflags.gni")
@@ -3026,7 +3027,8 @@ source_set("chromeos") {
   }
 }
 
-action("dbus_service_files") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("dbus_service_files") {
   sources = [
     "dbus/org.chromium.ChromeFeaturesService.conf",
     "dbus/org.chromium.ComponentUpdaterService.conf",
@@ -4039,7 +4041,8 @@ proto_library("print_job_info_proto") {
 
 device_policy_remover_path = "$target_gen_dir/device_policy_remover.cc"
 
-action("device_policy_remover_generate") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("device_policy_remover_generate") {
   script = "policy/tools/generate_device_policy_remover.py"
   descriptor_pool_path = "//third_party/protobuf/python"
   symbol_database_path = "$root_out_dir/pyproto"

chrome/browser/resources/chromeos/accessibility/common/run_jsbundler.gni

@@ -1,6 +1,7 @@
 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
+import("//build/config/python.gni")
 import("//chromecast/chromecast.gni")
 
 assert(is_chromeos || is_chromecast)
@@ -28,7 +29,9 @@ template("run_jsbundler") {
   } else {
     rewrite_rules = []
   }
-  action(target_name) {
+
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action(target_name) {
     script = "//chrome/browser/resources/chromeos/accessibility/chromevox/tools/jsbundler.py"
     inputs = jsbundler_modules
     sources = invoker.sources

chrome/browser/resources/optimize_webui.gni

@@ -2,8 +2,11 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
+
 template("node") {
-  action(target_name) {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action(target_name) {
     forward_variables_from(invoker, "*")
 
     # Declare dependencies to all involved tools.

chrome/installer/mini_installer/BUILD.gn

@@ -4,6 +4,7 @@
 
 import("//build/config/compiler/compiler.gni")
 import("//build/config/features.gni")
+import("//build/config/python.gni")
 import("//build/config/ui.gni")
 import("//chrome/process_version_rc_template.gni")
 import("//components/nacl/features.gni")
@@ -134,7 +135,8 @@ template("generate_mini_installer") {
   archive_name = target_name + "_archive"
   staging_dir = "$target_gen_dir/$target_name"
 
-  action(archive_name) {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action(archive_name) {
     script = "//chrome/tools/build/win/create_installer_archive.py"
 
     release_file = "chrome.release"

chrome/test/base/js2gtest.gni

@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
 import("//v8/gni/snapshot_toolchain.gni")
 import("//v8/gni/v8.gni")
 
@@ -53,7 +54,8 @@ template("js2gtest") {
     data += invoker.data
   }
 
-  action_foreach(action_name) {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action_foreach(action_name) {
     testonly = true
     visibility = [ ":$source_set_name" ]
     script = "//tools/gypv8sh.py"

chrome/test/data/media/engagement/preload/BUILD.gn

@@ -3,9 +3,11 @@
 # found in the LICENSE file.
 
 import("//build/compiled_action.gni")
+import("//build/config/python.gni")
 
 # Generates a proto file based on the real list.
-action_foreach("generate_preload_list") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action_foreach("generate_preload_list") {
   script = "//tools/media_engagement_preload/make_dafsa.py"
 
   sources = [ "test.json" ]

chrome/updater/mac/BUILD.gn

@@ -4,6 +4,7 @@
 
 import("//build/apple/tweak_info_plist.gni")
 import("//build/config/mac/rules.gni")
+import("//build/config/python.gni")
 import("//build/util/version.gni")
 import("//chrome/updater/branding.gni")
 
@@ -119,7 +120,8 @@ source_set("updater_setup_sources") {
   ]
 }
 
-action("updater_install_script") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("updater_install_script") {
   script = "embed_variables.py"
 
   inputs = [
@@ -139,7 +141,8 @@ action("updater_install_script") {
   ]
 }
 
-action("browser_install_script") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("browser_install_script") {
   script = "embed_variables.py"
 
   inputs = [

chrome/updater/win/installer/BUILD.gn

@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
 import("//build/timestamp.gni")
 import("//chrome/process_version_rc_template.gni")
 import("//testing/test.gni")
@@ -52,7 +53,8 @@ template("generate_installer") {
   archive_name = target_name + "_archive"
   staging_dir = "$target_gen_dir/$target_name"
 
-  action(archive_name) {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action(archive_name) {
     script = "create_installer_archive.py"
 
     release_file = "updater.release"

chromeos/ime/BUILD.gn

@@ -2,7 +2,10 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-action("gencode") {
+import("//build/config/python.gni")
+
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("gencode") {
   script = "gen_input_methods.py"
   sources = [ "//chromeos/ime/input_methods.txt" ]
   outputs = [ "$target_gen_dir/input_methods.h" ]

components/autofill_assistant/browser/devtools/BUILD.gn

@@ -2,6 +2,8 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
+
 devtools_domains = [
   "accessibility",
   "animation",
@@ -51,7 +53,8 @@ foreach(domain, devtools_domains) {
   ]
 }
 
-action("gen_devtools_client_api") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("gen_devtools_client_api") {
   script = "devtools_api/client_api_generator.py"
   deps = [ "//third_party/blink/public/devtools_protocol:protocol_version" ]
   inputs = [

components/metrics/structured/BUILD.gn

@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
 import("//testing/test.gni")
 
 # Structured metrics is subcomponent of UMA that gathers and reports structured
@@ -31,7 +32,8 @@ static_library("structured") {
   ]
 }
 
-action("gen_structured_events") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("gen_structured_events") {
   script = "//tools/metrics/structured/gen_events.py"
 
   # Re-generate the outputs if the codegen code changes:

components/policy/BUILD.gn

@@ -5,6 +5,7 @@
 import("//build/config/chrome_build.gni")
 import("//build/config/features.gni")
 import("//build/config/mac/base_rules.gni")
+import("//build/config/python.gni")
 import("//build/toolchain/toolchain.gni")
 import("//components/policy/resources/policy_templates.gni")
 import("//third_party/libprotobuf-mutator/fuzzable_proto_library.gni")
@@ -97,7 +98,8 @@ constants_source_path = "$target_gen_dir/policy_constants.cc"
 app_restrictions_path = "$target_gen_dir/app_restrictions.xml"
 risk_tag_header_path = "$target_gen_dir/risk_tag.h"
 
-action("policy_code_generate") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("policy_code_generate") {
   script = "tools/generate_policy_source.py"
   chrome_version_abspath = "//chrome/VERSION"
   chrome_version_path = rebase_path(chrome_version_abspath, root_build_dir)
@@ -141,7 +143,8 @@ action("policy_code_generate") {
   ]
 }
 
-action("full_runtime_code_generate") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("full_runtime_code_generate") {
   script = "tools/generate_policy_source.py"
   chrome_version_abspath = "//chrome/VERSION"
   chrome_version_path = rebase_path(chrome_version_abspath, root_build_dir)
@@ -187,7 +190,8 @@ grit("translate_policy_templates") {
 }
 
 # Generate the various templates and docs (admx, doc, json, etc.)
-action("policy_templates") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("policy_templates") {
   script = "tools/template_writers/template_formatter.py"
   chrome_version_abspath = "//chrome/VERSION"
   chrome_version_path = rebase_path(chrome_version_abspath, root_build_dir)

components/resources/BUILD.gn

@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 
 import("//build/config/android/config.gni")
+import("//build/config/python.gni")
 import("//components/safe_browsing/buildflags.gni")
 import("//printing/buildflags/buildflags.gni")
 import("//tools/grit/grit_rule.gni")
@@ -85,7 +86,8 @@ grit("components_scaled_resources") {
   output_dir = "$root_gen_dir/components"
 }
 
-action("about_credits") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("about_credits") {
   script = "//tools/licenses.py"
   depfile = "$target_gen_dir/$target_name.d"
 

components/resources/ssl/ssl_error_assistant/BUILD.gn

@@ -2,8 +2,11 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
+
 # Generate the binary proto form of "ssl_error_assistant" from the ascii proto.
-action("make_ssl_error_assistant_protobuf") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("make_ssl_error_assistant_protobuf") {
   script = "gen_ssl_error_assistant_proto.py"
 
   # The output goes in $target_gen_dir since that's where

components/safe_browsing/core/resources/BUILD.gn

@@ -2,10 +2,13 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
+
 # TODO(nparker): reduce the duplication between these two, somehow.
 
 # Generate the binary proto form of "file_types" from the ascii proto.
-action("make_file_types_protobuf") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("make_file_types_protobuf") {
   script = "gen_file_type_proto.py"
 
   # The output goes in $target_gen_dir since that's where
@@ -63,7 +66,8 @@ action("make_file_types_protobuf") {
 
 # Generate the binary proto for ALL platforms.  This is only run manually
 # when pushing the files to GCS for the component-updater to pick up.
-action("make_all_file_types_protobuf") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("make_all_file_types_protobuf") {
   script = "gen_file_type_proto.py"
 
   input_filename = "download_file_types.asciipb"

components/schema_org/BUILD.gn

@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 
 import("//build/compiled_action.gni")
+import("//build/config/python.gni")
 import("//testing/libfuzzer/fuzzer_test.gni")
 
 source_set("unit_tests") {
@@ -52,7 +53,8 @@ compiled_action("schema_org_name_data") {
   outputs = [ "$target_gen_dir/schema_org_name_data.json" ]
 }
 
-action("generate_schema_org_code") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("generate_schema_org_code") {
   script = "//components/schema_org/generate_schema_org_code.py"
 
   sources = [

components/strings/BUILD.gn

@@ -57,6 +57,11 @@ if (is_android) {
 }
 
 grit("components_chromium_strings") {
+  # TODO(crbug.com/1112471). For reasons I don't understand,
+  # IDS_ERRORPAGES_SUGGESTION_PROXY_DISABLE_PLATFORM is not defined
+  # on desktop linux when this is run under Python3. Fix this.
+  run_under_python2 = true
+
   source = "../components_chromium_strings.grd"
   outputs = [ "grit/components_chromium_strings.h" ]
   foreach(locale, locales_with_fake_bidi) {

components/variations/service/generate_ui_string_overrider.gni

@@ -2,6 +2,8 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
+
 # Runs the resources map generation script other the given header files to
 # produce an output file and a source_set to build it.
 #
@@ -30,7 +32,8 @@ template("generate_ui_string_overrider") {
   source_set_target_name = target_name
   gen_action_target_name = target_name + "_gen_sources"
 
-  action(gen_action_target_name) {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action(gen_action_target_name) {
     header_filename = "$target_gen_dir/" + invoker.header_filename
     source_filename = "$target_gen_dir/" + invoker.source_filename
 

components/viz/service/compositor_frame_fuzzer/BUILD.gn

@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
 import("//testing/libfuzzer/fuzzer_test.gni")
 import("//third_party/protobuf/proto_library.gni")
 
@@ -19,7 +20,8 @@ proto_library("compositor_frame_fuzzer_proto") {
 # The messages must be of type RenderPass, as defined in the proto2 file
 # compositor_frame_fuzzer.proto (these assumptions are all hardcoded into
 # generate_renderpass_binary.py)
-action_foreach("generate_seed_corpus") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action_foreach("generate_seed_corpus") {
   script = "generate_renderpass_binary.py"
   pyproto_path = "$root_out_dir/pyproto"
 

components/zucchini/fuzzers/BUILD.gn

@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
 import("//testing/libfuzzer/fuzzer_test.gni")
 import("//third_party/protobuf/proto_library.gni")
 
@@ -71,7 +72,8 @@ proto_library("zucchini_file_pair_proto") {
 # Disabled on Windows due to crbug/844826.
 if (current_toolchain == host_toolchain && !is_win) {
   # Raw Apply Fuzzer Seed:
-  action("zucchini_raw_apply_seed") {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action("zucchini_raw_apply_seed") {
     script = "generate_fuzzer_data.py"
 
     args = [
@@ -107,7 +109,8 @@ if (current_toolchain == host_toolchain && !is_win) {
   }
 
   # ZTF Apply Fuzzer Seed:
-  action("zucchini_ztf_apply_seed") {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action("zucchini_ztf_apply_seed") {
     script = "generate_fuzzer_data.py"
 
     # *.ztf files are expected to be valid ZTF format.

content/browser/tracing/BUILD.gn

@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
 import("//tools/grit/grit_rule.gni")
 
 # generate_about_tracing puts its files in this directory
@@ -11,7 +12,8 @@ tracing_gen_dir = "$root_gen_dir/content/browser/tracing"
 # this file to be in the same directory as the inputs.
 tracing_grd = "$tracing_gen_dir/tracing_resources.grd"
 
-action("generate_tracing_grd") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("generate_tracing_grd") {
   visibility = [ ":*" ]  # Depend on ":resources" to get this.
   script = "generate_trace_viewer_grd.py"
 

content/public/android/BUILD.gn

@@ -57,6 +57,9 @@ android_resources("content_java_resources") {
 }
 
 action_with_pydeps("generate_sandboxed_service_srcjar") {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  run_under_python2 = true
+
   script = "//content/public/android/generate_child_service.py"
 
   _srcjar_path = "${target_gen_dir}/${target_name}.srcjar"

gpu/config/BUILD.gn

@@ -5,6 +5,7 @@
 import("//build/config/chrome_build.gni")
 import("//build/config/chromecast_build.gni")
 import("//build/config/chromeos/ui_mode.gni")
+import("//build/config/python.gni")
 import("//build/config/ui.gni")
 import("//gpu/vulkan/features.gni")
 
@@ -31,7 +32,8 @@ process_json_outputs = [
   "$target_gen_dir/software_rendering_list_exceptions_autogen.h",
 ]
 
-action("process_json") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("process_json") {
   script = "process_json.py"
 
   inputs = [

headless/BUILD.gn

@@ -4,6 +4,7 @@
 
 import("//build/config/c++/c++.gni")
 import("//build/config/chrome_build.gni")
+import("//build/config/python.gni")
 import("//build/util/lastchange.gni")
 import("//build/util/process_version.gni")
 import("//headless/headless.gni")
@@ -77,7 +78,8 @@ repack("pak") {
   output = "$root_out_dir/headless_lib.pak"
 }
 
-action("embed_resources") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("embed_resources") {
   # TODO(altimin): Consider zipping file here, it can reduce size up to 80%.
   script = "lib/embed_data.py"
 

mojo/public/interfaces/bindings/tests/BUILD.gn

@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
 import("../../../tools/bindings/mojom.gni")
 
 group("test_data_deps") {
@@ -254,7 +255,8 @@ copy("validation_test_data") {
   outputs = [ "$root_gen_dir/layout_test_data/{{source_root_relative_dir}}/{{source_file_part}}" ]
 }
 
-action_foreach("validation_test_data_list") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action_foreach("validation_test_data_list") {
   testonly = true
   script = "//mojo/public/tools/bindings/gen_data_files_list.py"
   inputs = mojom_generator_sources

mojo/public/js/BUILD.gn

@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
 import("//third_party/closure_compiler/closure_args.gni")
 import("//third_party/closure_compiler/compile_js.gni")
@@ -9,7 +10,8 @@ import("//tools/grit/grit_rule.gni")
 
 interfaces_bindings_gen_dir = "$root_gen_dir/mojo/public/interfaces/bindings"
 
-action("bindings") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("bindings") {
   bindings_js_files = [
     # This must be the first file in the list, because it initializes global
     # variable |mojo| that the others need to refer to.
@@ -50,7 +52,8 @@ action("bindings") {
 }
 
 template("concatenate_files") {
-  action(target_name) {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action(target_name) {
     script = "//mojo/public/tools/bindings/concatenate-files.py"
     inputs = invoker.inputs
     output = "$target_gen_dir/${invoker.output}"
@@ -175,6 +178,8 @@ js_library("bindings_uncompiled") {
 }
 
 grit("resources") {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  run_under_python2 = true
   source = "mojo_bindings_resources.grd"
 
   outputs = [

mojo/public/tools/bindings/BUILD.gn

@@ -2,10 +2,12 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
 import("//third_party/jinja2/jinja2.gni")
 
-action("precompile_templates") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("precompile_templates") {
   sources = mojom_generator_sources
   sources += [
     "$mojom_generator_root/generators/cpp_templates/enum_macros.tmpl",

mojo/public/tools/bindings/mojom.gni

@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
 import("//third_party/closure_compiler/closure_args.gni")
 import("//third_party/closure_compiler/compile_js.gni")
 import("//third_party/protobuf/proto_library.gni")
@@ -629,7 +630,8 @@ template("mojom") {
       enabled_features += [ "is_win" ]
     }
 
-    action(parser_target_name) {
+    # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+    python2_action(parser_target_name) {
       script = mojom_parser_script
       inputs = mojom_parser_sources + [ build_metadata_filename ]
       sources = sources_list
@@ -651,7 +653,7 @@ template("mojom") {
         # Resolve relative input mojom paths against both the root src dir and
         # the root gen dir.
         "--input-root",
-        rebase_path("//"),
+        rebase_path("//."),
         "--input-root",
         rebase_path(root_gen_dir),
 
@@ -746,7 +748,8 @@ template("mojom") {
       }
     }
 
-    action(generator_cpp_message_ids_target_name) {
+    # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+    python2_action(generator_cpp_message_ids_target_name) {
       script = mojom_generator_script
       inputs = mojom_generator_sources + jinja2_sources
       sources = sources_list
@@ -785,7 +788,9 @@ template("mojom") {
     }
 
     generator_shared_target_name = "${target_name}_shared__generator"
-    action(generator_shared_target_name) {
+
+    # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+    python2_action(generator_shared_target_name) {
       visibility = [ ":*" ]
       script = mojom_generator_script
       inputs = mojom_generator_sources + jinja2_sources
@@ -904,7 +909,9 @@ template("mojom") {
 
     generator_mojolpm_proto_target_name =
         "${target_name}_mojolpm_proto_generator"
-    action(generator_mojolpm_proto_target_name) {
+
+    # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+    python2_action(generator_mojolpm_proto_target_name) {
       script = mojom_generator_script
       inputs = mojom_generator_sources + jinja2_sources
       sources = invoker.sources
@@ -1093,7 +1100,9 @@ template("mojom") {
       ]
 
       generator_target_name = "${target_name}${variant_suffix}__generator"
-      action(generator_target_name) {
+
+      # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+      python2_action(generator_target_name) {
         visibility = [ ":*" ]
         script = mojom_generator_script
         inputs = mojom_generator_sources + jinja2_sources
@@ -1273,7 +1282,9 @@ template("mojom") {
     }
     write_file(_typemap_config_filename, _rebased_typemap_configs, "json")
     _mojom_target_name = target_name
-    action(_typemap_validator_target_name) {
+
+    # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+    python2_action(_typemap_validator_target_name) {
       script = "$mojom_generator_root/validate_typemap_config.py"
       inputs = [ _typemap_config_filename ]
       outputs = [ _typemap_stamp_filename ]
@@ -1284,7 +1295,8 @@ template("mojom") {
       ]
     }
 
-    action(type_mappings_target_name) {
+    # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+    python2_action(type_mappings_target_name) {
       inputs =
           mojom_generator_sources + jinja2_sources + [ _typemap_stamp_filename ]
       outputs = [ type_mappings_path ]
@@ -1453,7 +1465,8 @@ template("mojom") {
 
       java_generator_target_name = target_name + "_java__generator"
       if (sources_list != []) {
-        action(java_generator_target_name) {
+        # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+        python2_action(java_generator_target_name) {
           script = mojom_generator_script
           inputs = mojom_generator_sources + jinja2_sources
           sources = sources_list
@@ -1492,7 +1505,9 @@ template("mojom") {
       }
 
       java_srcjar_target_name = target_name + "_java_sources"
-      action(java_srcjar_target_name) {
+
+      # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+      python2_action(java_srcjar_target_name) {
         script = "//build/android/gyp/zip.py"
         inputs = []
         if (output_file_base_paths != []) {
@@ -1551,7 +1566,9 @@ template("mojom") {
       !use_typescript_for_target) {
     if (sources_list != []) {
       generator_js_target_name = "${target_name}_js__generator"
-      action(generator_js_target_name) {
+
+      # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+      python2_action(generator_js_target_name) {
         script = mojom_generator_script
         inputs = mojom_generator_sources + jinja2_sources
         sources = sources_list
@@ -1791,7 +1808,9 @@ template("mojom") {
       # Generate Typescript bindings.
       generator_ts_target_name =
           "${target_name}_${dependency_type.name}__ts__generator"
-      action(generator_ts_target_name) {
+
+      # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+      python2_action(generator_ts_target_name) {
         script = mojom_generator_script
         inputs = mojom_generator_sources + jinja2_sources
         sources = sources_list
@@ -1858,7 +1877,8 @@ template("mojom") {
           "${target_name}_${dependency_type.name}__js__generator"
       generator_js_target_names += [ generator_js_target_name ]
 
-      action(generator_js_target_name) {
+      # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+      python2_action(generator_js_target_name) {
         script = "$mojom_generator_root/compile_typescript.py"
         sources = ts_outputs
         outputs = js_outputs

ppapi/native_client/nacl_test_data.gni

@@ -4,6 +4,7 @@
 
 import("//build/config/nacl/config.gni")
 import("//build/config/nacl/rules.gni")
+import("//build/config/python.gni")
 import("//components/nacl/features.gni")
 
 assert(enable_nacl)
@@ -182,7 +183,8 @@ template("nacl_test_data") {
     # This is a template so it can be invoked twice in the
     # defined(extra_tc_cpu) case below.
     template("nacl_test_data_pretranslate_pexe") {
-      action(target_name) {
+      # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+      python2_action(target_name) {
         translate_cpu = invoker.translate_cpu
 
         visibility = [ ":$nexe_copy_target_name" ]

ppapi/native_client/src/untrusted/pnacl_support_extension/BUILD.gn

@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
 import("//components/nacl/features.gni")
 
 assert(enable_nacl)
@@ -10,7 +11,8 @@ assert(enable_nacl)
 # toolchain and copies the latest PNaCl IRT shim library.
 # We could use 'copies', but we want to rename the files in a white-listed
 # way first.  Thus use an action.
-action("pnacl_support_extension") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("pnacl_support_extension") {
   script = "pnacl_component_crx_gen.py"
   inputs = [
     "//native_client/build/package_version/package_version.py",

remoting/host/BUILD.gn

@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
 import("//build/util/process_version.gni")
 import("//remoting/build/config/remoting_build.gni")
 
@@ -644,7 +645,8 @@ if (enable_remoting_host) {
     }
   }
 
-  action_foreach("remoting_native_messaging_manifests") {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action_foreach("remoting_native_messaging_manifests") {
     if (is_mac) {
       me2me_host_path = "/Library/PrivilegedHelperTools/$me2me_host_bundle_name/Contents/MacOS/$native_messaging_host_bundle_name/Contents/MacOS/native_messaging_host"
       it2me_host_path = "/Library/PrivilegedHelperTools/$me2me_host_bundle_name/Contents/MacOS/$remote_assistance_host_bundle_name/Contents/MacOS/remote_assistance_host"
@@ -686,7 +688,8 @@ if (enable_remoting_host) {
     ]
   }
 
-  action_foreach("remoting_infoplist_strings") {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action_foreach("remoting_infoplist_strings") {
     sources = [
       "it2me/remote_assistance_host-InfoPlist.strings.jinja2",
       "remoting_me2me_host-InfoPlist.strings.jinja2",

remoting/host/installer/BUILD.gn

@@ -2,9 +2,11 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
 import("//remoting/build/config/remoting_build.gni")
 
-action("credits") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("credits") {
   # We put this in $root_build_dir/gen/remoting instead of
   # $root_build_dir/gen/remoting/host (target_gen_dir) for
   # compatibility w/ GYP, since the installer needs the file to

remoting/host/installer/mac/BUILD.gn

@@ -2,11 +2,13 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
 import("//build/config/zip.gni")
 import("//chrome/installer/mac/mac_signing_sources.gni")
 import("//remoting/build/config/remoting_build.gni")
 
-action("remoting_me2me_host_archive") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("remoting_me2me_host_archive") {
   _installer_mac_files = [
     "do_signing.sh",
     "do_signing.props",

remoting/host/installer/win/BUILD.gn

@@ -2,10 +2,12 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
 import("//remoting/build/config/remoting_build.gni")
 import("//remoting/host/installer/win/generate_clsids.gni")
 
-action("remoting_me2me_host_archive") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("remoting_me2me_host_archive") {
   script = "//remoting/host/installer/build-installer-archive.py"
 
   sources = [ "//build/android/gyp/util/build_utils.py" ]

remoting/ios/app/resources/BUILD.gn

@@ -5,6 +5,7 @@
 import("//build/config/chrome_build.gni")
 import("//build/config/ios/asset_catalog.gni")
 import("//build/config/ios/rules.gni")
+import("//build/config/python.gni")
 import("//remoting/build/config/remoting_build.gni")
 import("//remoting/remoting_locales.gni")
 
@@ -87,7 +88,8 @@ appiconset("remoting_icons") {
 
 # i18n
 
-action("infoplist_strings") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("infoplist_strings") {
   _source = "InfoPlist.strings.jinja2"
   sources = [ _source ]
 

remoting/resources/BUILD.gn

@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
 import("//remoting/remoting_locales.gni")
 import("//tools/grit/grit_rule.gni")
 
@@ -13,7 +14,8 @@ group("resources") {
   ]
 }
 
-action("verify_resources") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("verify_resources") {
   script = "//remoting/tools/verify_resources.py"
 
   sources_to_verify = [
@@ -82,7 +84,8 @@ if (is_android) {
   }
 }
 
-action("copy_locales") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("copy_locales") {
   script = "../tools/build/remoting_copy_locales.py"
 
   # The gyp build calls out to Python, but the Python just computes a simple

remoting/tools/build/remoting_localize.gni

@@ -2,6 +2,8 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
+
 # Calls the remoting_localize script with a jinja2 template.
 #
 # Arguments
@@ -33,7 +35,8 @@
 #   deps (optional)
 #   visibility (optional)
 template("remoting_localize") {
-  action_foreach(target_name) {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action_foreach(target_name) {
     if (defined(invoker.visibility)) {
       visibility = invoker.visibility
     }

sandbox/policy/mac/BUILD.gn

@@ -2,7 +2,10 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-action_foreach("package_sb_files") {
+import("//build/config/python.gni")
+
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action_foreach("package_sb_files") {
   script = "package_sb_file.py"
   sources = [
     "audio.sb",

services/metrics/public/cpp/BUILD.gn

@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
 
 component("metrics_cpp") {
@@ -56,7 +57,8 @@ source_set("tests") {
   ]
 }
 
-action("gen_ukm_builders") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("gen_ukm_builders") {
   script = "//tools/metrics/ukm/gen_builders.py"
 
   # Re-generate the outputs if the codegen code changes:
@@ -64,7 +66,6 @@ action("gen_ukm_builders") {
     "//tools/metrics/ukm/builders_template.py",
     "//tools/metrics/ukm/decode_template.py",
     "//tools/metrics/ukm/codegen.py",
-    "//tools/metrics/ukm/gen_builders.py",
   ]
   sources = [ "//tools/metrics/ukm/ukm.xml" ]
 

third_party/blink/renderer/bindings/BUILD.gn

@@ -17,7 +17,8 @@ import("//third_party/blink/renderer/modules/modules_idl_files.gni")
 
 visibility = [ "//third_party/blink/renderer/*" ]
 
-action("interfaces_info") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("interfaces_info") {
   script = "$bindings_scripts_dir/compute_interfaces_info_overall.py"
 
   inputs = [
@@ -65,6 +66,9 @@ if (use_blink_v8_binding_new_idl_interface) {
 
 template("collect_idl_files") {
   action_with_pydeps(target_name) {
+    # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+    run_under_python2 = true
+
     script = "${bindings_scripts_dir}/collect_idl_files.py"
 
     inputs = invoker.inputs
@@ -139,6 +143,9 @@ collect_idl_files("web_idl_in_modules_for_testing") {
 }
 
 action_with_pydeps("web_idl_database") {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  run_under_python2 = true
+
   script = "${bindings_scripts_dir}/build_web_idl_database.py"
 
   input_data_files = get_target_outputs(":web_idl_in_core") +
@@ -168,6 +175,9 @@ action_with_pydeps("web_idl_database") {
 
 template("generate_bindings") {
   action_with_pydeps(target_name) {
+    # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+    run_under_python2 = true
+
     script = "${bindings_scripts_dir}/generate_bindings.py"
 
     if (defined(invoker.pool)) {
@@ -232,6 +242,9 @@ generate_bindings("generate_bindings_all") {
 }
 
 action_with_pydeps("generate_high_entropy_list") {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  run_under_python2 = true
+
   script = "${bindings_scripts_dir}/generate_high_entropy_list.py"
 
   web_idl_database_outputs = get_target_outputs(":web_idl_database")

third_party/blink/renderer/bindings/modules/v8/BUILD.gn

@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
 import("//third_party/blink/renderer/bindings/bindings.gni")
 import("//third_party/blink/renderer/bindings/generated_in_modules.gni")
 import("//third_party/blink/renderer/bindings/modules/v8/generated.gni")
@@ -247,7 +248,8 @@ blink_modules_sources("bindings_modules_impl") {
   ]
 }
 
-action("generate_v8_context_snapshot_external_references") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("generate_v8_context_snapshot_external_references") {
   script = "$bindings_scripts_dir/generate_v8_context_snapshot_external_references.py"
   idl_files =
       core_interface_idl_files_core_only +

third_party/blink/renderer/bindings/scripts/scripts.gni

@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
 import("//third_party/blink/renderer/build/scripts/scripts.gni")
 import("//third_party/blink/renderer/core/core_idl_files.gni")
 import("//third_party/blink/renderer/modules/modules_idl_files.gni")
@@ -65,7 +66,8 @@ idl_compiler_files = get_path_info(
 #   component_info_file = output pickle file for component wide info.
 #   deps = dependencies
 template("compute_interfaces_info") {
-  action(target_name) {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action(target_name) {
     script = "$bindings_scripts_dir/compute_interfaces_info_individual.py"
     if (defined(invoker.visibility)) {
       visibility = invoker.visibility
@@ -112,7 +114,8 @@ template("compute_interfaces_info") {
 #   output_file = The .in file to write, relative to the blink_gen_dir.
 #   suffix = (Optional) String to be passed to script via --suffix
 template("generate_event_interfaces") {
-  action(target_name) {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action(target_name) {
     # Write the file list to a unique temp file to avoid blowing out the
     # command line length limit.
     idl_files_list = "$target_gen_dir/${target_name}_file_list.tmp"
@@ -196,7 +199,8 @@ template("idl_compiler") {
 
   # Spawning a python process per IDL file is slow. Use a single action
   # instead (crbug.com/821256).
-  action(target_name) {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action(target_name) {
     script = _script
     inputs = _inputs
     public_deps = _public_deps
@@ -245,7 +249,8 @@ template("idl_compiler") {
 template("idl_impl") {
   dictionary_impl_output_dir = "$root_gen_dir/third_party/blink/renderer/"
 
-  action(target_name) {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action(target_name) {
     script = "//third_party/blink/renderer/bindings/scripts/idl_compiler.py"
     idl_files_list = "$target_gen_dir/${target_name}_file_list.tmp"
     write_file(idl_files_list, rebase_path(invoker.dict_idls, root_build_dir))
@@ -439,7 +444,8 @@ template("generate_global_constructors") {
 #   deps = dependencies
 #
 template("generate_origin_trial_features") {
-  action(target_name) {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action(target_name) {
     script = "//third_party/blink/renderer/bindings/scripts/generate_origin_trial_features.py"
 
     # Write the file list to a unique temp file to avoid blowing out the

third_party/blink/renderer/build/scripts/scripts.gni

@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
 import("//build/toolchain/toolchain.gni")
 import("//third_party/blink/renderer/config.gni")
 
@@ -91,7 +92,8 @@ make_core_generated_deps = [
 #  - //third_party/blink/renderer/build/scripts
 #  - //third_party
 template("blink_python_runner") {
-  action(target_name) {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action(target_name) {
     script = "$_scripts_dir/run_with_pythonpath.py"
     sources = [ invoker.script ]
     if (defined(invoker.sources)) {

third_party/blink/renderer/core/BUILD.gn

@@ -921,16 +921,22 @@ blink_python_runner("make_core_generated_css_tokenizer_codepoints") {
 blink_python_runner("make_core_generated_css_primitive_value_unit_trie") {
   visibility = []  # Allow re-assignment of list.
   visibility = [ ":*" ]
-  script = "../build/scripts/core/css/make_css_primitive_value_unit_trie.py"
+
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  script = "//build/util/python2_action.py"
 
   input_file = "css/css_primitive_value_units.json5"
   inputs = make_trie_helpers_files + [
              input_file,
+             "../build/scripts/core/css/make_css_primitive_value_unit_trie.py",
              "../build/scripts/core/css/templates/css_primitive_value_unit_trie.cc.tmpl",
            ]
   outputs = [ "$blink_core_output_dir/css/css_primitive_value_unit_trie.cc" ]
 
   args = [
+    rebase_path(
+        "../build/scripts/core/css/make_css_primitive_value_unit_trie.py",
+        root_build_dir),
     rebase_path(input_file, root_build_dir),
     "--output_dir",
     "$rel_blink_core_gen_dir/css",
@@ -1003,6 +1009,7 @@ blink_python_runner("make_core_generated_origin_trials") {
     "$rel_blink_core_gen_dir/origin_trials",
   ]
 }
+
 blink_python_runner("make_core_generated_web_origin_trials") {
   script = "../build/scripts/make_web_origin_trials.py"
 

third_party/closure_compiler/compile_js.gni

@@ -2,6 +2,8 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
+
 import("//third_party/closure_compiler/closure_args.gni")
 
 declare_args() {
@@ -53,7 +55,8 @@ polymer_externs = "$externs_path/polymer-1.0.js"
 #   }
 
 template("js_library") {
-  action(target_name) {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action(target_name) {
     script = "$script_path/js_library.py"
     forward_variables_from(invoker,
                            [
@@ -153,7 +156,8 @@ template("js_library") {
 #   }
 
 template("js_binary") {
-  action(target_name) {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action(target_name) {
     script = "$script_path/js_binary.py"
     forward_variables_from(invoker,
                            [

third_party/dom_distiller_js/BUILD.gn

@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
 import("//third_party/protobuf/proto_library.gni")
 
 group("proto") {
@@ -50,7 +51,8 @@ proto_library("json_values_converter_test_proto") {
   generator_plugin_options = "output_dir=:"
 }
 
-action("json_values_converter_tests") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("json_values_converter_tests") {
   _stamp = "$target_gen_dir/json_values_converter_tests.stamp"
   deps = [ ":json_values_converter_test_proto" ]
   inputs = [ "test_sample_json_converter.h.golden" ]

third_party/opus/BUILD.gn

@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 
 import("//build/config/arm.gni")
+import("//build/config/python.gni")
 import("//testing/test.gni")
 
 # If fixed point implementation shall be used (otherwise float).
@@ -21,7 +22,8 @@ use_opus_x86_optimization =
 # If OPUS Run Time CPU Detections (RTCD) shall be used.
 # Based on the conditions in celt/arm/armcpu.c:
 # defined(_MSC_VER) || defined(__linux__).
-use_opus_arm_rtcd = current_cpu == "arm" && (is_win || is_android || is_linux || is_chromeos)
+use_opus_arm_rtcd =
+    current_cpu == "arm" && (is_win || is_android || is_linux || is_chromeos)
 
 config("opus_config") {
   include_dirs = [ "src/include" ]
@@ -168,7 +170,8 @@ config("opus_test_no_nonnull_config") {
 }
 
 if (use_opus_arm_rtcd) {
-  action("convert_rtcd_assembler") {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action("convert_rtcd_assembler") {
     script = "convert_rtcd_assembler.py"
     outputs = [ "$target_gen_dir/celt_pitch_xcorr_arm_gnu.S" ]
     args = [
@@ -372,8 +375,8 @@ static_library("opus") {
     "src/src/opus_multistream_decoder.c",
     "src/src/opus_multistream_encoder.c",
     "src/src/opus_private.h",
-    "src/src/opus_projection_encoder.c",
     "src/src/opus_projection_decoder.c",
+    "src/src/opus_projection_encoder.c",
     "src/src/repacketizer.c",
     "src/src/tansig_table.h",
   ]

third_party/protobuf/proto_library.gni

@@ -303,10 +303,20 @@ template("proto_library") {
       ":$javascript_name",
       ":$source_set_name",
     ]
-    script = "//tools/protoc_wrapper/protoc_wrapper.py"
+    if ((defined(invoker.run_under_python2) && invoker.run_under_python2) ||
+        true) {
+      # TODO(crbug.com/1112471) - get all users of this to run cleanly under
+      # Python 3 and then remove this option.
+      script = "//build/util/python2_action.py"
+      args = [ rebase_path("//tools/protoc_wrapper/protoc_wrapper.py",
+                           root_build_dir) ] + protos
+    } else {
+      script = "//tools/protoc_wrapper/protoc_wrapper.py"
+      args = protos
+    }
+
     sources = proto_sources
     outputs = get_path_info(protogens + protogens_cc + protogens_js, "abspath")
-    args = protos
 
     if (defined(invoker.testonly)) {
       testonly = invoker.testonly

third_party/quic_trace/BUILD.gn

@@ -1,8 +1,10 @@
+import("//build/config/python.gni")
 import("//third_party/protobuf/proto_library.gni")
 
 # Since most of the Chromium uses proto_lite, modify the source proto file to
 # use the lite runtime.
-action("quic_trace_proto_lite_runtime") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("quic_trace_proto_lite_runtime") {
   script = "append_lite_runtime.py"
   inputs = [ "src/lib/quic_trace.proto" ]
   outputs = [ "$target_gen_dir/quic_trace.proto" ]
@@ -19,6 +21,9 @@ proto_library("quic_trace_proto") {
     "//net/third_party/quiche:quic_test_tools_core",
   ]
 
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  run_under_python2 = true
+
   sources = [ "$target_gen_dir/quic_trace.proto" ]
   proto_deps = [ ":quic_trace_proto_lite_runtime" ]
   component_build_force_source_set = true

third_party/wayland/wayland_protocol.gni

@@ -9,6 +9,7 @@
 #    sources = [ "foo.xml" ]
 #  }
 
+import("//build/config/python.gni")
 import("//third_party/wayland/features.gni")
 
 template("wayland_protocol") {
@@ -33,7 +34,8 @@ template("wayland_protocol") {
   source_set_name = "${target_name}"
 
   # Action which runs wayland-scanner to generate the code.
-  action(action_name) {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action(action_name) {
     visibility = [ ":$source_set_name" ]
     script = "//third_party/wayland/wayland_scanner_wrapper.py"
     sources = invoker.sources

tools/grit/grit_rule.gni

@@ -67,11 +67,17 @@
 #   configs (optional)
 #       List of additional configs to be applied to the generated target.
 #
+#   run_under_python2 (optional)
+#       If true, this is always run under Python2; if false (the default),
+#       will be run under whatever script_executable actually is.
+#       TODO(crbug.com/1112471): Find all users of this and get them to
+#       run cleanly under Python3, then remove this option.
 #   deps  (optional)
 #   testonly (optional)
 #   visibility  (optional)
 #       Normal meaning.
 #
+#
 # Example
 #
 #   grit("my_resources") {
@@ -138,12 +144,27 @@ template("grit") {
 
   _grit_custom_target = target_name + "_grit"
   action(_grit_custom_target) {
+    # TODO(crbug.com/1112471): Remove the 'true' branch so that we can start
+    # running *some* grit invocations under python3, and then get them
+    # all to work under python3.
+    if ((defined(invoker.run_under_python2) && invoker.run_under_python2) ||
+        true) {
+      script = "//build/util/python2_action.py"
+      args = [ rebase_path("//tools/grit/grit.py", root_build_dir) ]
+      inputs = [
+        "//tools/grit/grit.py",
+        invoker.source,
+      ]
+    } else {
+      script = "//tools/grit/grit.py"
+      args = []
+      inputs = [ invoker.source ]
+    }
+
     testonly = defined(invoker.testonly) && invoker.testonly
 
-    script = "//tools/grit/grit.py"
     depfile = "$target_gen_dir/$target_name.d"
 
-    inputs = [ invoker.source ]
     deps = [ "//tools/grit:grit_sources" ]
     outputs = [ "${depfile}.stamp" ] + _grit_outputs + _pak_info_outputs
 
@@ -179,19 +200,19 @@ template("grit") {
       inputs += rebase_path(_rel_inputs, ".", root_build_dir)
     }
 
-    args = [
-             "-i",
-             _rebased_source_path,
-             "build",
-             "-o",
-             rebase_path(_output_dir, root_build_dir),
-             "--depdir",
-             ".",
-             "--depfile",
-             rebase_path(depfile, root_build_dir),
-             "--write-only-new=1",
-             "--depend-on-stamp",
-           ] + _grit_flags
+    args += [
+              "-i",
+              _rebased_source_path,
+              "build",
+              "-o",
+              rebase_path(_output_dir, root_build_dir),
+              "--depdir",
+              ".",
+              "--depfile",
+              rebase_path(depfile, root_build_dir),
+              "--write-only-new=1",
+              "--depend-on-stamp",
+            ] + _grit_flags
 
     # Add brotli executable if using brotli.
     if (defined(invoker.use_brotli) && invoker.use_brotli) {

tools/grit/preprocess_grit.gni

@@ -2,10 +2,12 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
 import("//tools/grit/grit_defines.gni")
 
 template("preprocess_grit") {
-  action(target_name) {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action(target_name) {
     script = "//tools/grit/preprocess_grit.py"
 
     if (defined(invoker.deps)) {

tools/json_schema_compiler/json_features.gni

@@ -2,6 +2,8 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/python.gni")
+
 # Generates the FeatureProviders files for extension features files.
 # The following variables are required:
 #   sources: The features.json files to use.
@@ -27,7 +29,8 @@ template("json_features") {
     "$target_gen_dir/$base_filename.h",
   ]
 
-  action(action_name) {
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action(action_name) {
     visibility = [ ":$source_set_name" ]
     sources = invoker.sources
     script = "$compiler_root/feature_compiler.py"

tools/json_schema_compiler/json_schema_api.gni

@@ -36,6 +36,8 @@
 #     A specific visibility to apply for the generated static library. If
 #     omitted, visibility will be inherited from the invoker.
 
+import("//build/config/python.gni")
+
 # NOTE: Common variables here for when multiple templates use them.
 compiler_root = "//tools/json_schema_compiler"
 compiler_script = "$compiler_root/compiler.py"
@@ -317,7 +319,9 @@ template("generated_types") {
   root_target_name = target_name
 
   schema_generator_name = target_name + "_schema_generator"
-  action_foreach(schema_generator_name) {
+
+  # TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+  python2_action_foreach(schema_generator_name) {
     visibility = [ ":$root_target_name" ]
     script = compiler_script
     sources = invoker.sources

tools/usb_gadget/BUILD.gn

@@ -2,7 +2,10 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-action("usb_gadget") {
+import("//build/config/python.gni")
+
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("usb_gadget") {
   script = "//tools/usb_gadget/package.py"
   inputs = [
     "__init__.py",

ui/ozone/BUILD.gn

@@ -4,6 +4,7 @@
 
 import("//build/buildflag_header.gni")
 import("//build/config/ozone.gni")
+import("//build/config/python.gni")
 import("//build/config/ui.gni")
 import("//gpu/vulkan/features.gni")
 import("//testing/test.gni")
@@ -282,7 +283,8 @@ static_library("test_support") {
   public_deps = [ ":test_support_internal" ]
 }
 
-action("generate_ozone_platform_list") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("generate_ozone_platform_list") {
   script = "generate_ozone_platform_list.py"
   outputs = [
     platform_list_cc_file,
@@ -301,7 +303,8 @@ action("generate_ozone_platform_list") {
   visibility += [ "//media:*" ]
 }
 
-action("generate_constructor_list") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("generate_constructor_list") {
   script = "generate_constructor_list.py"
 
   inputs = [ platform_list_txt_file ]
@@ -321,7 +324,8 @@ action("generate_constructor_list") {
   deps = [ ":generate_ozone_platform_list" ]
 }
 
-action("generate_test_support_constructor_list") {
+# TODO(crbug.com/1112471): Get this to run cleanly under Python 3.
+python2_action("generate_test_support_constructor_list") {
   script = "generate_constructor_list.py"
 
   inputs = [ platform_list_txt_file ]