Add UMA histogram timers for ProcessManager and BackgroundContentsService startup.

chrome/browser/background/background_contents_service.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/browser/background/background_contents_service.h"
 
 #include "apps/app_load_service.h"
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/message_loop/message_loop.h"
+#include "base/metrics/histogram.h"

[Ilya Sherman, 2015/02/05 02:50:26]

nit: Please include histogram_macros instead.

[Yoyo Zhou, 2015/02/05 03:08:02]

Done.

 #include "base/prefs/pref_service.h"
 #include "base/prefs/scoped_user_pref_update.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/time/time.h"
 #include "base/values.h"
 #include "chrome/browser/background/background_contents_service_factory.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/extensions/extension_service.h"
@@ skipping 313 matching lines @@
   // Listen for extension uninstall, load, unloaded notification.
   extension_registry_observer_.Add(extensions::ExtensionRegistry::Get(profile));
 }
 
 void BackgroundContentsService::Observe(
     int type,
     const content::NotificationSource& source,
     const content::NotificationDetails& details) {
   switch (type) {
     case extensions::NOTIFICATION_EXTENSIONS_READY_DEPRECATED: {
+      const base::TimeTicks start_time = base::TimeTicks::Now();
       Profile* profile = content::Source<Profile>(source).ptr();
       LoadBackgroundContentsFromManifests(profile);
       LoadBackgroundContentsFromPrefs(profile);
       SendChangeNotification(profile);
+      UMA_HISTOGRAM_TIMES("BackgroundContentsService.LoadOnExtensionsReadyTime",
+                          base::TimeTicks::Now() - start_time);
       break;
     }
     case chrome::NOTIFICATION_BACKGROUND_CONTENTS_DELETED:
       BackgroundContentsShutdown(
           content::Details<BackgroundContents>(details).ptr());
       SendChangeNotification(content::Source<Profile>(source).ptr());
       break;
     case chrome::NOTIFICATION_BACKGROUND_CONTENTS_CLOSED:
       DCHECK(IsTracked(content::Details<BackgroundContents>(details).ptr()));
       UnregisterBackgroundContents(
@@ skipping 411 matching lines @@
     bool user_gesture,
     bool* was_blocked) {
   Browser* browser = chrome::FindLastActiveWithProfile(
       Profile::FromBrowserContext(new_contents->GetBrowserContext()),
       chrome::GetActiveDesktop());
   if (browser) {
     chrome::AddWebContents(browser, NULL, new_contents, disposition,
                            initial_pos, user_gesture, was_blocked);
   }
 }