Remove all remaining traces of MessageLoopProxy.

components/history/core/browser/history_service.cc

 // Copyright (c) 2012 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.
 
 // The history system runs on a background thread so that potentially slow
 // database operations don't delay the browser. This backend processing is
 // represented by HistoryBackend. The HistoryService's job is to dispatch to
 // that thread.
 //
 // Main thread                       History thread
@@ skipping 289 matching lines @@
 }
 
 base::CancelableTaskTracker::TaskId HistoryService::ScheduleDBTask(
     std::unique_ptr<HistoryDBTask> task,
     base::CancelableTaskTracker* tracker) {
   DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   base::CancelableTaskTracker::IsCanceledCallback is_canceled;
   base::CancelableTaskTracker::TaskId task_id =
       tracker->NewTrackedTaskId(&is_canceled);
-  // Use base::ThreadTaskRunnerHandler::Get() to get a message loop proxy to
+  // Use base::ThreadTaskRunnerHandler::Get() to get a task runner for
   // the current message loop so that we can forward the call to the method
   // HistoryDBTask::DoneRunOnMainThread() in the correct thread.
   thread_->task_runner()->PostTask(
       FROM_HERE, base::Bind(&HistoryBackend::ProcessDBTask,
                             history_backend_.get(), base::Passed(&task),
                             base::ThreadTaskRunnerHandle::Get(), is_canceled));
   return task_id;
 }
 
 void HistoryService::FlushForTest(const base::Closure& flushed) {
@@ skipping 811 matching lines @@
   return favicon_changed_callback_list_.Add(callback);
 }
 
 void HistoryService::NotifyFaviconsChanged(const std::set<GURL>& page_urls,
                                            const GURL& icon_url) {
   DCHECK(thread_checker_.CalledOnValidThread());
   favicon_changed_callback_list_.Notify(page_urls, icon_url);
 }
 
 }  // namespace history