Remove MessageLoop::current() from chrome_metrics_service_client.cc

content/browser/histogram_synchronizer.h

 // 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.
 
 #ifndef CONTENT_BROWSER_HISTOGRAM_SYNCHRONIZER_H_
 #define CONTENT_BROWSER_HISTOGRAM_SYNCHRONIZER_H_
 
 #include <string>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/singleton.h"
 #include "base/synchronization/lock.h"
+#include "base/task_runner.h"
 #include "base/time/time.h"
 #include "content/browser/histogram_subscriber.h"
 
-namespace base {
-class MessageLoop;
-}
-
 namespace content {
 
 // This class maintains state that is used to upload histogram data from the
 // various child processes, into the browser process. Such transactions are
 // usually instigated by the browser. In general, a child process will respond
 // by gathering snapshots of all internal histograms, calculating what has
 // changed since its last upload, and transmitting a pickled collection of
 // deltas.
 //
 // There are actually two modes of update request.  One is synchronous (and
@@ skipping 29 matching lines @@
   // Return pointer to the singleton instance for the current process, or NULL
   // if none.
   static HistogramSynchronizer* GetInstance();
 
   // Contact all processes, and get them to upload to the browser any/all
   // changes to histograms. This method is called from about:histograms.
   static void FetchHistograms();
 
   // Contact all child processes, and get them to upload to the browser any/all
   // changes to histograms.  When all changes have been acquired, or when the
-  // wait time expires (whichever is sooner), post the callback to the
-  // specified message loop. Note the callback is posted exactly once.
-  static void FetchHistogramsAsynchronously(base::MessageLoop* callback_thread,
-                                            const base::Closure& callback,
-                                            base::TimeDelta wait_time);
+  // wait time expires (whichever is sooner), post the callback to the specified
+  // TaskRunner. Note the callback is posted exactly once.
+  static void FetchHistogramsAsynchronously(
+      scoped_refptr<base::TaskRunner> task_runner,
+      const base::Closure& callback,
+      base::TimeDelta wait_time);
 
  private:
   friend struct base::DefaultSingletonTraits<HistogramSynchronizer>;
 
   class RequestContext;
 
   HistogramSynchronizer();
   ~HistogramSynchronizer() override;
 
   // Establish a new sequence number, and use it to notify all processes
@@ skipping 13 matching lines @@
                           int pending_processes,
                           bool end) override;
 
   // Send histogram_data back to caller and also record that we are waiting
   // for one less histogram data from child process for the given sequence
   // number. This method is accessible on UI thread.
   void OnHistogramDataCollected(
       int sequence_number,
       const std::vector<std::string>& pickled_histograms) override;
 
-  // Set the callback_thread_ and callback_ members. If these members already
-  // had values, then as a side effect, post the old callback_ to the old
-  // callaback_thread_.  This side effect should not generally happen, but is in
-  // place to assure correctness (that any tasks that were set, are eventually
-  // called, and never merely discarded).
-  void SetCallbackTaskAndThread(base::MessageLoop* callback_thread,
+  // Set the |callback_task_runner_| and |callback_| members. If these members
+  // already had values, then as a side effect, post the old |callback_| to the
+  // old |callback_task_runner_|. This side effect should not generally happen,
+  // but is in place to assure correctness (that any tasks that were set, are
+  // eventually called, and never merely discarded).
+  void SetTaskRunnerAndCallback(scoped_refptr<base::TaskRunner> task_runner,
                                 const base::Closure& callback);
 
   void ForceHistogramSynchronizationDoneCallback(int sequence_number);
 
   // Internal helper function, to post task, and record callback stats.
-  void InternalPostTask(base::MessageLoop* thread,
+  void InternalPostTask(scoped_refptr<base::TaskRunner> task_runner,
                         const base::Closure& callback);
 
   // Gets a new sequence number to be sent to processes from browser process.
   int GetNextAvailableSequenceNumber(ProcessHistogramRequester requester);
 
   // This lock_ protects access to all members.
   base::Lock lock_;
 
   // When a request is made to asynchronously update the histograms, we store
-  // the task and thread we use to post a completion notification in
-  // callback_ and callback_thread_.
+  // the task and TaskRunner we use to post a completion notification in
+  // |callback_| and |callback_task_runner_|.
   base::Closure callback_;
-  base::MessageLoop* callback_thread_;
+  scoped_refptr<base::TaskRunner> callback_task_runner_;
 
   // We don't track the actual processes that are contacted for an update, only
   // the count of the number of processes, and we can sometimes time-out and
   // give up on a "slow to respond" process.  We use a sequence_number to be
   // sure a response from a process is associated with the current round of
   // requests (and not merely a VERY belated prior response).
   // All sequence numbers used are non-negative.
   // last_used_sequence_number_ is the most recently used number (used to avoid
   // reuse for a long time).
   int last_used_sequence_number_;
 
   // The sequence number used by the most recent asynchronous update request to
   // contact all processes.
   int async_sequence_number_;
 
   DISALLOW_COPY_AND_ASSIGN(HistogramSynchronizer);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_HISTOGRAM_SYNCHRONIZER_H_