Move the thread hop for UMA user actions from content:: to base::.

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>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/feature_list.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/memory/memory_pressure_monitor.h"
 #include "base/memory/ptr_util.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
+#include "base/metrics/user_metrics.h"
 #include "base/pending_task.h"
 #include "base/power_monitor/power_monitor.h"
 #include "base/power_monitor/power_monitor_device_source.h"
 #include "base/process/process_metrics.h"
 #include "base/profiler/scoped_profile.h"
 #include "base/run_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_split.h"
 #include "base/system_monitor/system_monitor.h"
@@ skipping 550 matching lines @@
     TRACE_EVENT0("startup", "BrowserMainLoop::Subsystem:OnlineStateObserver");
     online_state_observer_.reset(new BrowserOnlineStateObserver);
   }
 
   {
     system_stats_monitor_.reset(
         new base::trace_event::TraceEventSystemStatsMonitor(
             base::ThreadTaskRunnerHandle::Get()));
   }
 
+  {

[Alexei Svitkine (slow), 2016/04/22 14:30:13]

Nit: why the {}'s?

+    base::SetRecordActionTaskRunner(
+        BrowserThread::GetMessageLoopProxyForThread(BrowserThread::UI));
+  }
+
 #if defined(OS_WIN)
   if (base::win::GetVersion() >= base::win::VERSION_WIN8)
     screen_orientation_delegate_.reset(new ScreenOrientationDelegateWin());
 #endif
 
   // TODO(boliu): kSingleProcess check is a temporary workaround for
   // in-process Android WebView. crbug.com/503724 tracks proper fix.
   if (!parsed_command_line_.HasSwitch(switches::kSingleProcess)) {
     base::DiscardableMemoryAllocator::SetInstance(
         HostDiscardableSharedMemoryManager::current());
@@ skipping 888 matching lines @@
   audio_task_runner = audio_thread_->task_runner();
   worker_task_runner = audio_thread_->task_runner();
   monitor_task_runner = io_thread_->task_runner();
 #endif  // defined(OS_MACOSX)
   audio_manager_ = media::AudioManager::Create(
       std::move(audio_task_runner), std::move(worker_task_runner),
       std::move(monitor_task_runner), MediaInternals::GetInstance());
 }
 
 }  // namespace content