Create TaskScheduler in BrowserMainLoop constructor.

content/browser/browser_main_loop.cc

 // Copyright (c) 2012 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 "content/browser/browser_main_loop.h"
 
 #include <stddef.h>
 
 #include <string>
 #include <utility>
@@ skipping 513 matching lines @@
       result_code_(RESULT_CODE_NORMAL_EXIT),
       created_threads_(false),
       // ContentMainRunner should have enabled tracing of the browser process
       // when kTraceStartup or kTraceConfigFile is in the command line.
       is_tracing_startup_for_duration_(
           parameters.command_line.HasSwitch(switches::kTraceStartup) ||
           (tracing::TraceConfigFile::GetInstance()->IsEnabled() &&
            tracing::TraceConfigFile::GetInstance()->GetStartupDuration() > 0)) {
   DCHECK(!g_current_browser_main_loop);
   g_current_browser_main_loop = this;
+
+  // Use an empty string as TaskScheduler name to match the suffix of browser
+  // process TaskScheduler histograms.
+  base::TaskScheduler::Create("");
 }
 
 BrowserMainLoop::~BrowserMainLoop() {
   DCHECK_EQ(this, g_current_browser_main_loop);
   ui::Clipboard::DestroyClipboardForCurrentThread();
   g_current_browser_main_loop = NULL;
 }
 
 void BrowserMainLoop::Init() {
   TRACE_EVENT0("startup", "BrowserMainLoop::Init");
@@ skipping 400 matching lines @@
     startup_task_runner_->RunAllTasksNow();
   }
 #else
   startup_task_runner_->RunAllTasksNow();
 #endif
 }
 
 int BrowserMainLoop::CreateThreads() {
   TRACE_EVENT0("startup,rail", "BrowserMainLoop::CreateThreads");
 
-  auto task_scheduler_init_params =
-      GetContentClient()->browser()->GetTaskSchedulerInitParams();
-  if (!task_scheduler_init_params)
-    task_scheduler_init_params = GetDefaultTaskSchedulerInitParams();
-  DCHECK(task_scheduler_init_params);
-
-  base::TaskScheduler::CreateAndSetDefaultTaskScheduler(
-      "", *task_scheduler_init_params.get());
+  {
+    auto task_scheduler_init_params =
+        GetContentClient()->browser()->GetTaskSchedulerInitParams();
+    if (!task_scheduler_init_params)
+      task_scheduler_init_params = GetDefaultTaskSchedulerInitParams();
+    DCHECK(task_scheduler_init_params);
+    base::TaskScheduler::GetInstance()->Start(
+        *task_scheduler_init_params.get());
+  }
 
   GetContentClient()->browser()->PerformExperimentalTaskSchedulerRedirections();
 
   base::Thread::Options io_message_loop_options;
   io_message_loop_options.message_loop_type = base::MessageLoop::TYPE_IO;
   base::Thread::Options ui_message_loop_options;
   ui_message_loop_options.message_loop_type = base::MessageLoop::TYPE_UI;
 
   const bool redirect_nonUInonIO_browser_threads =
       GetContentClient()
@@ skipping 779 matching lines @@
         BrowserThread::GetTaskRunnerForThread(BrowserThread::FILE),
         MediaInternals::GetInstance());
   }
   CHECK(audio_manager_);
 
   audio_system_ = media::AudioSystemImpl::Create(audio_manager_.get());
   CHECK(audio_system_);
 }
 
 }  // namespace content