Only record the execution time during startup.

components/history/core/browser/top_sites_backend.cc

Index: components/history/core/browser/top_sites_backend.cc
diff --git a/components/history/core/browser/top_sites_backend.cc b/components/history/core/browser/top_sites_backend.cc
index 2383c1c9d213510dc217bc28465667d05dda2392..dc0773c8e7934e19ca8250924862cac9f1671719 100644
--- a/components/history/core/browser/top_sites_backend.cc
+++ b/components/history/core/browser/top_sites_backend.cc
@@ -19,6 +19,18 @@
 
 namespace history {
 
+TopSitesBackend::HistogramRecording TopSitesBackend::histogram_recorded_ =
+    HISTOGRAM_RECORDING_NOT_YET;
+
+// static
+void TopSitesBackend::IncraseHistogramRecordingStatus() {
+  if (histogram_recorded_ == HISTOGRAM_RECORDING_NOT_YET) {
+    histogram_recorded_ = HISTOGRAM_RECORDING_IN_PROGRESS;
+  } else if (histogram_recorded_ == HISTOGRAM_RECORDING_IN_PROGRESS) {
+    histogram_recorded_ = HISTOGRAM_RECORDING_DONE;
+  }
+}
+
 TopSitesBackend::TopSitesBackend(
     const scoped_refptr<base::SingleThreadTaskRunner>& db_task_runner)
     : db_(new TopSitesDatabase()), db_task_runner_(db_task_runner) {
@@ -47,10 +59,12 @@ void TopSitesBackend::GetMostVisitedThumbnails(
       base::Bind(callback, thumbnails));
 }
 
-void TopSitesBackend::UpdateTopSites(const TopSitesDelta& delta) {
+void TopSitesBackend::UpdateTopSites(const TopSitesDelta& delta,
+                                     const CallLocation location) {
   db_task_runner_->PostTask(
       FROM_HERE,
-      base::Bind(&TopSitesBackend::UpdateTopSitesOnDBThread, this, delta));
+      base::Bind(&TopSitesBackend::UpdateTopSitesOnDBThread, this, delta,
+                 location));
 }
 
 void TopSitesBackend::SetPageThumbnail(const MostVisitedURL& url,
@@ -101,7 +115,8 @@ void TopSitesBackend::GetMostVisitedThumbnailsOnDBThread(
   }
 }
 
-void TopSitesBackend::UpdateTopSitesOnDBThread(const TopSitesDelta& delta) {
+void TopSitesBackend::UpdateTopSitesOnDBThread(
+    const TopSitesDelta& delta, const CallLocation location) {
   TRACE_EVENT0("startup", "history::TopSitesBackend::UpdateTopSitesOnDBThread");
 
   if (!db_)
@@ -120,8 +135,15 @@ void TopSitesBackend::UpdateTopSitesOnDBThread(const TopSitesDelta& delta) {
   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::TimeTicks::Now() - begin_time);
+  // If this is initiated from TopSitesImpl::OnGotMostVisitedThumbnails, and
+  // |histogram_recorded_| indicates that the histogram recording is in
+  // progress, records the function execution time.
+  if (location == CALL_LOCATION_FROM_ON_GOT_MOST_VISITED_THUMBNAILS &&
+      histogram_recorded_ == HISTOGRAM_RECORDING_IN_PROGRESS) {
+    UMA_HISTOGRAM_TIMES("History.UpdateTopSitesOnDBThread_Startup_Time",
+                        base::TimeTicks::Now() - begin_time);
+    IncraseHistogramRecordingStatus();
+  }
 }
 
 void TopSitesBackend::SetPageThumbnailOnDBThread(const MostVisitedURL& url,