Eliminated the last few uses of MessageLoop::QuitTask in chrome/

chrome/browser/visitedlink/visitedlink_master.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 "chrome/browser/visitedlink/visitedlink_master.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #include <io.h>
 #include <shlobj.h>
@@ skipping 829 matching lines @@
 
       // Send an update notification to all child processes.
       listener_->NewTable(shared_memory_);
 
       WriteFullTable();
     }
   }
   table_builder_ = NULL;  // Will release our reference to the builder.
 
   // Notify the unit test that the rebuild is complete (will be NULL in prod.)
-  if (rebuild_complete_task_.get()) {
-    rebuild_complete_task_->Run();
-    rebuild_complete_task_.reset(NULL);
+  if (!rebuild_complete_task_.is_null()) {
+    rebuild_complete_task_.Run();
+    rebuild_complete_task_.Reset();
   }
 }
 
 void VisitedLinkMaster::WriteToFile(FILE* file,
                                     off_t offset,
                                     void* data,
                                     int32 data_size) {
 #ifndef NDEBUG
   posted_asynchronous_operation_ = true;
 #endif
@@ skipping 83 matching lines @@
 }
 
 void VisitedLinkMaster::TableBuilder::OnCompleteMainThread() {
   if (master_)
     master_->OnTableRebuildComplete(success_, fingerprints_);
 
   // WILL (generally) DELETE THIS! This balances the AddRef in
   // VisitedLinkMaster::RebuildTableFromHistory.
   Release();
 }