[Media Router] Custom Controls 1 - Add MediaStatus, MediaRouteController, and mojo interfaces

chrome/browser/media/router/mojo/media_route_controller.cc

+// Copyright 2017 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/media/router/mojo/media_route_controller.h"
+
+#include <utility>
+
+#include "base/time/time.h"
+#include "chrome/browser/media/router/media_route_status_observer.h"
+#include "chrome/browser/media/router/media_router.h"
+#include "chrome/browser/media/router/media_status.h"
+#include "chrome/browser/media/router/mojo/media_router.mojom.h"
+#include "mojo/public/cpp/bindings/interface_request.h"
+
+namespace media_router {
+
+MediaRouteController::MediaRouteController(
+    mojom::MediaControllerPtr media_controller,
+    base::Closure destroyer_callback)
+    : destroyer_callback_(destroyer_callback),
+      media_controller_(std::move(media_controller)),
+      binding_(this) {}
+MediaRouteController::~MediaRouteController() {}
+
+void MediaRouteController::Play() {
+  media_controller_->Play();
+}
+
+void MediaRouteController::Pause() {
+  media_controller_->Pause();
+}
+
+void MediaRouteController::Seek(base::TimeDelta time) {
+  media_controller_->Seek(time);
+}
+
+void MediaRouteController::SetMute(bool mute) {
+  media_controller_->SetMute(mute);
+}
+
+void MediaRouteController::SetVolume(float volume) {
+  media_controller_->SetVolume(volume);
+}
+
+void MediaRouteController::AddObserver(MediaRouteStatusObserver* observer) {
+  observers_.AddObserver(observer);
+}
+
+void MediaRouteController::RemoveObserver(MediaRouteStatusObserver* observer) {
+  observers_.RemoveObserver(observer);
+  if (!observers_.might_have_observers()) {
+    destroyer_callback_.Run();
+    // |this| gets destroyed here!
+  }

[imcheng, 2017/03/11 03:07:52]

1) If the associated MediaRoute is terminated, how do we notify the observers to
clean up?
2) Have you considered other approaches to make the ownership model more clear?
Here's a suggestion:

- MediaRouter returns a scoped_refpr<MediaRouteController> to callers, who
retains a reference to it as long as it is in use.
- MediaRouter itself holds a raw pointer in the internal MediaRoute ID to
controller mapping.
- When the ref count reaches zero, MediaRouteController will be deleted. At that
time, it should be removed from MediaRouter's mapping.
- If the associated MediaRoute is terminated while the controller is in use,
MediaRouter can send a signal to other observers to drop their references.

Let's chat about this with Mark on Monday?

+}
+
+void MediaRouteController::OnMediaStatusUpdated(const MediaStatus& status) {
+  for (MediaRouteStatusObserver& observer : observers_)
+    observer.OnMediaStatusUpdated(status);
+}
+
+mojom::MediaStatusObserverPtr MediaRouteController::GetObserverPtr() {
+  return binding_.CreateInterfacePtrAndBind();
+}
+
+}  // namespace media_router