Add/Update external Reclient build instructions

Bug: b/291868532
Change-Id: I54e6225ab01e12141957949d5c8c35b32e5062d5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5159847
Reviewed-by: Takuto Ikuta <tikuta@chromium.org>
Commit-Queue: Andrew Williams <awillia@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1244750}

docs/android_build_instructions.md

@@ -161,6 +161,28 @@ non-WebView targets. This is also allowed for Monochrome, but only when not set
 as the WebView provider.
 ***
 
+### Faster builds
+
+This section contains some things you can change to speed up your builds,
+sorted so that the things that make the biggest difference are first.
+
+#### Use Reclient
+
+*** note
+**Warning:** If you are a Google employee, do not follow the instructions below.
+See
+[go/building-android-chrome#initialize-remote-execution-distributed-builds](https://goto.google.com/building-android-chrome#initialize-remote-execution-distributed-builds)
+instead.
+***
+
+Chromium's build can be sped up significantly by using a remote execution system
+compatible with [REAPI](https://github.com/bazelbuild/remote-apis). This allows
+you to benefit from remote caching and executing many build actions in parallel
+on a shared cluster of workers.
+
+To use Reclient, follow the corresponding
+[Linux build instructions](linux/build_instructions.md#use-reclient).
+
 ## Build Chromium
 
 Build Chromium with Ninja using the command:

docs/android_cast_build_instructions.md

@@ -139,6 +139,28 @@ $ gn gen --args='target_os="android" is_cast_android=true' out/Default
 Also be aware that some scripts (e.g. `tombstones.py`, `adb_gdb.py`)
 require you to set `CHROMIUM_OUTPUT_DIR=out/Default`.
 
+### Faster builds
+
+This section contains some things you can change to speed up your builds,
+sorted so that the things that make the biggest difference are first.
+
+#### Use Reclient
+
+*** note
+**Warning:** If you are a Google employee, do not follow the instructions below.
+See
+[go/building-android-chrome#initialize-remote-execution-distributed-builds](https://goto.google.com/building-android-chrome#initialize-remote-execution-distributed-builds)
+instead.
+***
+
+Chromium's build can be sped up significantly by using a remote execution system
+compatible with [REAPI](https://github.com/bazelbuild/remote-apis). This allows
+you to benefit from remote caching and executing many build actions in parallel
+on a shared cluster of workers.
+
+To use Reclient, follow the corresponding
+[Linux build instructions](linux/build_instructions.md#use-reclient).
+
 ## Build cast\_shell\_apk
 
 Build `cast_shell_apk` with Ninja using the command:

docs/ios/build_instructions.md

@@ -136,6 +136,22 @@ You can also follow the manual instructions on the
 [Mac page](../mac_build_instructions.md), but make sure you set the
 GN arg `target_os="ios"`.
 
+### Faster builds
+
+This section contains some things you can change to speed up your builds,
+sorted so that the things that make the biggest difference are first.
+
+#### Use Reclient
+
+Google employees should use Reclient, a distributed compilation system. Detailed
+information is available internally but the relevant gn arg is:
+* `use_remoteexec = true`
+
+Google employees can visit
+[go/building-chrome-mac#using-remote-execution](https://goto.google.com/building-chrome-mac#using-remote-execution)
+for more information. For external contributors, Reclient does not support iOS
+builds.
+
 ## Building for device
 
 To be able to build and run Chromium and the tests for devices, you need to

docs/linux/build_instructions.md

@@ -153,11 +153,12 @@ $ gn gen out/Default
 This section contains some things you can change to speed up your builds,
 sorted so that the things that make the biggest difference are first.
 
-#### Use reclient
+#### Use Reclient
 
 *** note
 **Warning:** If you are a Google employee, do not follow the instructions below.
-See [go/chrome-linux-build#setup-remote-execution](http://go/chrome-linux-build#setup-remote-execution)
+See
+[go/chrome-linux-build#setup-remote-execution](https://goto.google.com/chrome-linux-build#setup-remote-execution)
 instead.
 ***
 
@@ -172,7 +173,7 @@ For contributors who have
 RBE backend paid by Google. Note that reclient for external contributors is a
 best-effort process. We do not guarantee when you will be invited. Reach out to
 [reclient-users@chromium.org](https://groups.google.com/a/chromium.org/g/reclient-users)
-if you have some questions about reclient usages.
+if you have any questions about reclient usage.
 
 To get started, you need access to an REAPI-compatible backend. The following
 instructions assume that you received an invitation from Google to use

docs/mac_build_instructions.md

@@ -154,6 +154,17 @@ in your args.gn to disable debug symbols altogether.  This makes both full
 rebuilds and linking faster (at the cost of not getting symbolized backtraces
 in gdb).
 
+#### Use Reclient
+
+In addition, Google employees should use Reclient, a distributed compilation system.
+Detailed information is available internally but the relevant gn arg is:
+* `use_remoteexec = true`
+
+Google employees can visit
+[go/building-chrome-mac#using-remote-execution](https://goto.google.com/building-chrome-mac#using-remote-execution)
+for more information. For external contributors, Reclient does not support Mac
+builds.
+
 #### CCache
 
 You might also want to [install ccache](ccache_mac.md) to speed up the build.

docs/windows_build_instructions.md

@@ -242,20 +242,19 @@ local variable or type information. With `symbol_level = 0` there is no
 source-level debugging but call stacks still have function names. Changing
 `symbol_level` requires recompiling everything.
 
+When invoking ninja, specify 'chrome' as the target to avoid building all test
+binaries as well.
+
 #### Use Reclient
 
-In addition, Google employees should use reclient, a distributed compilation system.
+In addition, Google employees should use Reclient, a distributed compilation system.
 Detailed information is available internally but the relevant gn arg is:
 * `use_remoteexec = true`
 
 Google employees can visit
-[go/building-chrome-win#setup-remote-execution](http://go/building-chrome-win#setup-remote-execution)
-for more information.
-
-When invoking ninja, specify 'chrome' as the target to avoid building all test
-binaries as well.
-
-Still, builds will take many hours on many machines.
+[go/building-chrome-win#setup-remote-execution](https://goto.google.com/building-chrome-win#setup-remote-execution)
+for more information. For external contributors, Reclient does not support
+Windows builds.
 
 #### Use Goma (deprecated)