Only record the execution time during startup.

chrome/browser/history/top_sites_impl.h

 // Copyright (c) 2013 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 CHROME_BROWSER_HISTORY_TOP_SITES_IMPL_H_
 #define CHROME_BROWSER_HISTORY_TOP_SITES_IMPL_H_
 
 #include <list>
 #include <set>
 #include <string>
@@ skipping 80 matching lines @@
   bool loaded() const override;
   bool AddForcedURL(const GURL& url, const base::Time& time) override;
 
   // RefcountedKeyedService:
   void ShutdownOnUIThread() override;
 
  protected:
   ~TopSitesImpl() override;
 
  private:
+  // TODO(yiyaoliu): Remove the enums and related code when crbug/223430 is
+  // fixed.
+  // An enum representing different situations under which function
+  // SetTopSites can be initiated.
+  // This is needed because a histogram is used to record speed related metrics
+  // when SetTopSites are initiated from OnGotMostVisitedThumbnails, which
+  // usually happens early and might affect Chrome startup speed.
+  enum CallLocation {
+    // SetTopSites is called from function OnGotMostVisitedThumbnails.
+    CALL_LOCATION_FROM_ON_GOT_MOST_VISITED_THUMBNAILS,
+    // All other situations.
+    CALL_LOCATION_FROM_OTHER_PLACES
+  };
+
   friend class TopSitesImplTest;
   FRIEND_TEST_ALL_PREFIXES(TopSitesImplTest, DiffMostVisited);
   FRIEND_TEST_ALL_PREFIXES(TopSitesImplTest, DiffMostVisitedWithForced);
 
   typedef base::Callback<void(const MostVisitedURLList&,
                               const MostVisitedURLList&)> PendingCallback;
 
   typedef std::pair<GURL, Images> TempImage;
   typedef std::list<TempImage> TempImages;
   typedef std::vector<PendingCallback> PendingCallbacks;
@@ skipping 77 matching lines @@
   void Observe(int type,
                const content::NotificationSource& source,
                const content::NotificationDetails& details) override;
 
   // Updates URLs in |cache_| and the db (in the background).
   // The non-forced URLs in |new_top_sites| replace those in |cache_|.
   // The forced URLs of |new_top_sites| are merged with those in |cache_|,
   // if the list of forced URLs overflows, the oldest ones are dropped.
   // All mutations to cache_ *must* go through this. Should
   // be called from the UI thread.
-  void SetTopSites(const MostVisitedURLList& new_top_sites);
+  void SetTopSites(const MostVisitedURLList& new_top_sites,
+                   const CallLocation location);
 
   // Returns the number of most visited results to request from history. This
   // changes depending upon how many urls have been blacklisted. Should be
   // called from the UI thread.
   int num_results_to_request_from_history() const;
 
   // Invoked when transitioning to LOADED. Notifies any queued up callbacks.
   // Should be called from the UI thread.
   void MoveStateToLoaded();
 
@@ skipping 60 matching lines @@
   // enough Top Sites (new profile), we store it until the next
   // SetNonForcedTopSites call.
   TempImages temp_images_;
 
   // URL List of prepopulated page.
   PrepopulatedPageList prepopulated_pages_;
 
   // Are we loaded?
   bool loaded_;
 
+  // Have the SetTopSites execution time related histograms been recorded?
+  // The histogram should only be recorded once for each Chrome execution.
+  static bool histogram_recorded_;
+
   ScopedObserver<HistoryService, HistoryServiceObserver>
       history_service_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(TopSitesImpl);
 };
 
 }  // namespace history
 
 #endif  // CHROME_BROWSER_HISTORY_TOP_SITES_IMPL_H_