Record the time to update top sites through db thread to understand if this is low and how slow it …

components/history/core/browser/top_sites_backend.cc

 // 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.
 
 #include "components/history/core/browser/top_sites_backend.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/files/file_path.h"
 #include "base/location.h"
 #include "base/memory/ref_counted.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/single_thread_task_runner.h"
 #include "base/task/cancelable_task_tracker.h"
+#include "base/trace_event/trace_event.h"
 #include "components/history/core/browser/top_sites_database.h"
 #include "sql/connection.h"
 
 namespace history {
 
 TopSitesBackend::TopSitesBackend(
     const scoped_refptr<base::SingleThreadTaskRunner>& db_task_runner)
     : db_(new TopSitesDatabase()), db_task_runner_(db_task_runner) {
   DCHECK(db_task_runner_);
 }
@@ skipping 68 matching lines @@
     scoped_refptr<MostVisitedThumbnails> thumbnails) {
   DCHECK(db_task_runner_->BelongsToCurrentThread());
 
   if (db_) {
     db_->GetPageThumbnails(&(thumbnails->most_visited),
                            &(thumbnails->url_to_images_map));
   }
 }
 
 void TopSitesBackend::UpdateTopSitesOnDBThread(const TopSitesDelta& delta) {
+  TRACE_EVENT0("startup", "history::TopSitesBackend::UpdateTopSitesOnDBThread");
+
   if (!db_)
     return;
 
+  // TODO(yiyaoliu): Remove the histogram and related code when crbug/223430 is
+  // fixed.
+  base::Time begin_time = base::Time::Now();

[sky, 2015/03/20 14:58:22]

Shouldn't we use timeticks for this sort of stuff?

[yao, 2015/03/20 18:06:01]

Done.

+
   for (size_t i = 0; i < delta.deleted.size(); ++i)
     db_->RemoveURL(delta.deleted[i]);
 
   for (size_t i = 0; i < delta.added.size(); ++i)
     db_->SetPageThumbnail(delta.added[i].url, delta.added[i].rank, Images());
 
   for (size_t i = 0; i < delta.moved.size(); ++i)
     db_->UpdatePageRank(delta.moved[i].url, delta.moved[i].rank);
+
+  UMA_HISTOGRAM_TIMES("History.UpdateTopSitesOnDBThreadTime",
+                      base::Time::Now() - begin_time);
 }
 
 void TopSitesBackend::SetPageThumbnailOnDBThread(const MostVisitedURL& url,
                                                  int url_rank,
                                                  const Images& thumbnail) {
   if (!db_)
     return;
 
   db_->SetPageThumbnail(url, url_rank, thumbnail);
 }
 
 void TopSitesBackend::ResetDatabaseOnDBThread(const base::FilePath& file_path) {
   DCHECK(db_task_runner_->BelongsToCurrentThread());
   db_.reset(NULL);
   sql::Connection::Delete(db_path_);
   db_.reset(new TopSitesDatabase());
   InitDBOnDBThread(db_path_);
 }
 
 }  // namespace history