[headless] Initialize Bluetooth on Linux with DBus

When using the --headless option with a normal Chrome build the
Bluetooth subsystem is fully enabled but the call to initialize the
connection to the BlueZ service over DBus was missing, leading to a
CHECK failure.

This change copies the initialization steps from the normal Chrome
startup sequence when DBus is enabled in the build.

Bug: 1093456
Change-Id: I171fbaa957acdcff521e020733d3024acf771e80
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2240303
Commit-Queue: Reilly Grant <reillyg@chromium.org>
Commit-Queue: Andrey Kosyakov <caseq@chromium.org>
Auto-Submit: Reilly Grant <reillyg@chromium.org>
Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#777191}

headless/BUILD.gn

@@ -311,6 +311,7 @@ component("headless_non_renderer") {
     "lib/browser/headless_browser_impl_mac.mm",
     "lib/browser/headless_browser_main_parts.cc",
     "lib/browser/headless_browser_main_parts.h",
+    "lib/browser/headless_browser_main_parts_linux.cc",
     "lib/browser/headless_browser_main_parts_mac.mm",
     "lib/browser/headless_devtools.cc",
     "lib/browser/headless_devtools.h",
@@ -377,6 +378,7 @@ component("headless_non_renderer") {
 
   data_deps = []
   data = []
+  defines = []
 
   if (enable_basic_printing) {
     public_deps += [ "//skia" ]
@@ -491,6 +493,11 @@ component("headless_non_renderer") {
     deps += [ "//ui/ozone" ]
   }
 
+  if (use_dbus) {
+    defines += [ "USE_DBUS" ]
+    deps += [ "//device/bluetooth" ]
+  }
+
   if (headless_fontconfig_utils && !is_fuchsia) {
     deps += [ ":headless_fontconfig_utils" ]
   }

headless/lib/DEPS

@@ -2,6 +2,9 @@ specific_include_rules = {
   "headless_browser_browsertest.cc": [
     "+third_party/crashpad/crashpad/client",
   ],
+  "headless_browser_main_parts_linux.cc": [
+    "+device/bluetooth",
+  ],
   "headless_content_client.cc": [
       "+components/embedder_support/origin_trials",
   ],

headless/lib/browser/headless_browser_main_parts.h

@@ -8,6 +8,7 @@
 #include <memory>
 
 #include "base/files/file_path.h"
+#include "build/build_config.h"
 #include "content/public/browser/browser_main_parts.h"
 #include "content/public/common/main_function_params.h"
 #include "headless/public/headless_browser.h"
@@ -31,7 +32,9 @@ class HeadlessBrowserMainParts : public content::BrowserMainParts {
 #if defined(OS_MACOSX)
   void PreMainMessageLoopStart() override;
 #endif
-
+#if defined(OS_LINUX)
+  void PostMainMessageLoopStart() override;
+#endif
   void QuitMainMessageLoop();
 
  private:

headless/lib/browser/headless_browser_main_parts_linux.cc

@@ -0,0 +1,18 @@
+// 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.
+
+#include "headless/lib/browser/headless_browser_main_parts.h"
+
+#include "build/build_config.h"
+#include "device/bluetooth/dbus/bluez_dbus_manager.h"
+
+namespace headless {
+
+void HeadlessBrowserMainParts::PostMainMessageLoopStart() {
+#if defined(USE_DBUS) && !defined(OS_CHROMEOS)
+  bluez::BluezDBusManager::Initialize(/*system_bus=*/nullptr);
+#endif
+}
+
+}  // namespace headless