Motown: Implement MediaTimelineController and use it.

services/media/framework/util/callback_joiner.h

 // Copyright 2016 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 MOJO_SERVICES_MEDIA_FRAMEWORK_UTIL_CALLBACK_JOINER_H_
 #define MOJO_SERVICES_MEDIA_FRAMEWORK_UTIL_CALLBACK_JOINER_H_
 
 #include <memory>
 
 #include "base/logging.h"
@@ skipping 55 matching lines @@
 
   // Indicates the initiation of a child operation. Every call to Spawn should
   // be matched by a subsequent call to Complete.
   void Spawn() { ++counter_; }
 
   // Indicates the completion of a child operation.
   void Complete() {
     DCHECK(counter_ != 0);
     --counter_;
     if (counter_ == 0) {
-      mojo::Callback<void()> join_callback;
+      Callback<void()> join_callback;
       join_callback = join_callback_;
       join_callback_.reset();
       join_callback.Run();
     }
   }
 
   // Calls Spawn and returns a new callback, which calls Complete. THIS METHOD
   // WILL ONLY WORK IF THERE IS ALREADY A SHARED POINTER TO THIS OBJECT.
   std::function<void()> NewCallback() {
     Spawn();
     std::shared_ptr<CallbackJoiner> this_ptr = shared_from_this();
     DCHECK(!this_ptr.unique());
     return [this_ptr]() {
       DCHECK(this_ptr);
       this_ptr->Complete();
     };
   }
 
   // Specifies a callback to be called when all child operations have completed.
   // If no child operations are currently pending, the callback is called
   // immediately. If child operations are pending, the callback is copied. The
   // copy called later (and reset) when all child oeprations have completed.
   // Only one callback at a time can be registered with WhenJoined.
-  void WhenJoined(const mojo::Callback<void()>& join_callback) {
+  void WhenJoined(const Callback<void()>& join_callback) {
     DCHECK(join_callback_.is_null());
     if (counter_ == 0) {
       join_callback.Run();
     } else {
       join_callback_ = join_callback;
     }
   }
 
   // Cancels a callback registered with WhenJoined if it hasn't run yet. The
   // return value indicates whether a callback was cancelled.
   bool Cancel() {
     bool result = !join_callback_.is_null();
     join_callback_.reset();
     return result;
   }
 
  private:
   size_t counter_ = 0;
-  mojo::Callback<void()> join_callback_;
+  Callback<void()> join_callback_;
 };
 
 }  // namespace media
 }  // namespace mojo
 
 #endif  // MOJO_SERVICES_MEDIA_FRAMEWORK_UTIL_CALLBACK_JOINER_H_