Profiler-instrumentation of the startup time.

chrome/app/chrome_main_delegate.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 "chrome/app/chrome_main_delegate.h"
 
 #include "base/base_paths.h"
 #include "base/command_line.h"
 #include "base/cpu.h"
 #include "base/files/file_path.h"
 #include "base/i18n/rtl.h"
 #include "base/lazy_instance.h"
 #include "base/message_loop/message_loop.h"
 #include "base/metrics/statistics_recorder.h"
 #include "base/path_service.h"
 #include "base/process/memory.h"
 #include "base/process/process_handle.h"
+#include "base/profiler/scoped_tracker.h"
 #include "base/strings/string_util.h"
 #include "build/build_config.h"
 #include "chrome/browser/chrome_content_browser_client.h"
 #include "chrome/browser/defaults.h"
 #include "chrome/common/chrome_constants.h"
 #include "chrome/common/chrome_content_client.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/chrome_paths_internal.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/chrome_version_info.h"
@@ skipping 936 matching lines @@
 }
 
 content::ContentUtilityClient*
 ChromeMainDelegate::CreateContentUtilityClient() {
 #if defined(CHROME_MULTIPLE_DLL_BROWSER)
   return NULL;
 #else
   return g_chrome_content_utility_client.Pointer();
 #endif
 }
+
+bool ChromeMainDelegate::EnableProfilerRecording() {
+  switch (chrome::VersionInfo::GetChannel()) {
+    case chrome::VersionInfo::CHANNEL_UNKNOWN:
+    case chrome::VersionInfo::CHANNEL_CANARY:
+      tracked_objects::ScopedTracker::Enable();

[vadimt, 2015/03/12 18:23:03]

We don't need BOTH returning bool and enabling.

[yao, 2015/03/12 18:32:19]

I don't really have a strong opinion, but what's the benefit of enabling it from
the caller instead of here? 

[vadimt, 2015/03/12 18:37:26]

Hypothetically, another implementation may override this, and there will be
duplication of tracked_objects::ScopedTracker::Enable();

So, I have a slight preference for simply returning bool, but it's up to you.

[yao, 2015/03/13 15:24:49]

Changed as you suggested. 

+      return true;
+    case chrome::VersionInfo::CHANNEL_DEV:
+    case chrome::VersionInfo::CHANNEL_BETA:
+    case chrome::VersionInfo::CHANNEL_STABLE:
+    default:
+      // Don't enable instrumentation.
+      return false;
+  }
+}