Remove dead code

chrome/browser/history/top_sites_impl.cc

Index: chrome/browser/history/top_sites_impl.cc
diff --git a/chrome/browser/history/top_sites_impl.cc b/chrome/browser/history/top_sites_impl.cc
index d1fd053df57c59a336fe0995a1d102431ddc496e..544da6350887ae166f62b3d98559142ae86b19e2 100644
--- a/chrome/browser/history/top_sites_impl.cc
+++ b/chrome/browser/history/top_sites_impl.cc
@@ -128,7 +128,7 @@ void TopSitesImpl::Init(const base::FilePath& db_name) {
   backend_->GetMostVisitedThumbnails(
       base::Bind(&TopSitesImpl::OnGotMostVisitedThumbnails,
                  base::Unretained(this)),
-      &cancelable_task_tracker_);
+      &backend_task_tracker_);
 }
 
 bool TopSitesImpl::SetPageThumbnail(const GURL& url,
@@ -378,7 +378,8 @@ void TopSitesImpl::Shutdown() {
   // Cancel all requests so that the service doesn't callback to us after we've
   // invoked Shutdown (this could happen if we have a pending request and
   // Shutdown is invoked).
-  history_consumer_.CancelAllRequests();
+  history_task_tracker_.TryCancelAll();
+  backend_task_tracker_.TryCancelAll();
   backend_->Shutdown();
 }
 
@@ -444,10 +445,10 @@ void TopSitesImpl::DiffMostVisited(const MostVisitedURLList& old_list,
   }
 }
 
-CancelableRequestProvider::Handle TopSitesImpl::StartQueryForMostVisited() {
+base::CancelableTaskTracker::TaskId TopSitesImpl::StartQueryForMostVisited() {
   DCHECK(loaded_);
   if (!profile_)
-    return 0;
+    return base::CancelableTaskTracker::kBadTaskId;
 
   HistoryService* hs = HistoryServiceFactory::GetForProfile(
       profile_, Profile::EXPLICIT_ACCESS);
@@ -458,9 +459,9 @@ CancelableRequestProvider::Handle TopSitesImpl::StartQueryForMostVisited() {
         kDaysOfHistory,
         base::Bind(&TopSitesImpl::OnTopSitesAvailableFromHistory,
                    base::Unretained(this)),
-        &cancelable_task_tracker_);

[blundell, 2014/07/03 08:29:12]

is this a bugfix?

[sdefresne, 2014/07/22 14:29:06]

This is unnecessary and removed.

+        &history_task_tracker_);
   }
-  return 0;
+  return base::CancelableTaskTracker::kBadTaskId;
 }
 
 bool TopSitesImpl::IsKnownURL(const GURL& url) {