Only record the execution time during startup.

components/history/core/browser/top_sites_backend.h

 // Copyright (c) 2011 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.
 
 #ifndef COMPONENTS_HISTORY_CORE_BROWSER_TOP_SITES_BACKEND_H_
 #define COMPONENTS_HISTORY_CORE_BROWSER_TOP_SITES_BACKEND_H_
 
 #include "base/callback.h"
 #include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
@@ skipping 27 matching lines @@
 
   // Schedules the db to be shutdown.
   void Shutdown();
 
   // Fetches MostVisitedThumbnails.
   void GetMostVisitedThumbnails(
       const GetMostVisitedThumbnailsCallback& callback,
       base::CancelableTaskTracker* tracker);
 
   // Updates top sites database from the specified delta.
-  void UpdateTopSites(const TopSitesDelta& delta);
+  // The bool param is used for knowing whether this function is called during
+  // startup or not, thus histogram value could be recorded accordingly.
+  // TODO(yiyaoliu): Remove this when crbug/223430 is fixed.
+  void UpdateTopSites(const TopSitesDelta& delta, bool startup);

[sky, 2015/03/31 23:58:49]

Same thing about an enum here too.

[yao, 2015/04/01 21:43:00]

Done.

 
   // Sets the thumbnail.
   void SetPageThumbnail(const MostVisitedURL& url,
                         int url_rank,
                         const Images& thumbnail);
 
   // Deletes the database and recreates it.
   void ResetDatabase();
 
   // Schedules a request that does nothing on the DB thread, but then notifies
@@ skipping 11 matching lines @@
   void InitDBOnDBThread(const base::FilePath& path);
 
   // Shuts down the db.
   void ShutdownDBOnDBThread();
 
   // Does the work of getting the most visted thumbnails.
   void GetMostVisitedThumbnailsOnDBThread(
       scoped_refptr<MostVisitedThumbnails> thumbnails);
 
   // Updates top sites.
-  void UpdateTopSitesOnDBThread(const TopSitesDelta& delta);
+  // The bool param is used for knowing whether this function is called during
+  // startup or not, thus histogram value could be recorded accordingly.
+  // TODO(yiyaoliu): Remove this when crbug/223430 is fixed.
+  void UpdateTopSitesOnDBThread(const TopSitesDelta& delta, bool startup);
 
   // Sets the thumbnail.
   void SetPageThumbnailOnDBThread(const MostVisitedURL& url,
                                   int url_rank,
                                   const Images& thumbnail);
 
   // Resets the database.
   void ResetDatabaseOnDBThread(const base::FilePath& file_path);
 
   base::FilePath db_path_;
 
   scoped_ptr<TopSitesDatabase> db_;
   scoped_refptr<base::SingleThreadTaskRunner> db_task_runner_;
 
   DISALLOW_COPY_AND_ASSIGN(TopSitesBackend);
 };
 
 }  // namespace history
 
 #endif  // COMPONENTS_HISTORY_CORE_BROWSER_TOP_SITES_BACKEND_H_