Implement MediaSession on top of the WebMediaPlayerDelegate.

content/renderer/media/renderer_webmediaplayer_delegate.cc

 // Copyright 2015 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 "content/renderer/media/renderer_webmediaplayer_delegate.h"
 
 #include <stdint.h>
 
 #include "content/common/frame_messages.h"
 #include "content/public/renderer/render_frame.h"
 #include "third_party/WebKit/public/platform/WebMediaPlayer.h"
 
 namespace media {
 
 RendererWebMediaPlayerDelegate::RendererWebMediaPlayerDelegate(
     content::RenderFrame* render_frame)
     : RenderFrameObserver(render_frame) {}
 
 RendererWebMediaPlayerDelegate::~RendererWebMediaPlayerDelegate() {}
 
-void RendererWebMediaPlayerDelegate::DidPlay(blink::WebMediaPlayer* player) {
-  has_played_media_ = true;
-  Send(new FrameHostMsg_MediaPlayingNotification(
-      routing_id(), reinterpret_cast<int64_t>(player), player->hasVideo(),
-      player->hasAudio(), player->isRemote()));
-}
-
-void RendererWebMediaPlayerDelegate::DidPause(blink::WebMediaPlayer* player) {
-  Send(new FrameHostMsg_MediaPausedNotification(
-      routing_id(), reinterpret_cast<int64_t>(player)));
-}
-
-void RendererWebMediaPlayerDelegate::PlayerGone(blink::WebMediaPlayer* player) {
-  DidPause(player);
+// static
+int64_t RendererWebMediaPlayerDelegate::GetPlayerId(Observer* observer) {
+  return reinterpret_cast<int64_t>(observer);
 }
 
 void RendererWebMediaPlayerDelegate::AddObserver(Observer* observer) {
   observer_list_.AddObserver(observer);
 }
 
 void RendererWebMediaPlayerDelegate::RemoveObserver(Observer* observer) {
   observer_list_.RemoveObserver(observer);
 }
 
+void RendererWebMediaPlayerDelegate::DidPlay(Observer* observer,
+                                             bool has_video,
+                                             bool has_audio,
+                                             bool is_remote,
+                                             base::TimeDelta duration) {
+  DCHECK(observer_list_.HasObserver(observer));
+  has_played_media_ = true;
+  Send(new FrameHostMsg_MediaPlayingNotification(
+      routing_id(), GetPlayerId(observer), has_video, has_audio, is_remote,
+      duration));
+}
+
+void RendererWebMediaPlayerDelegate::DidPause(Observer* observer,
+                                              bool reached_end_of_stream) {
+  DCHECK(observer_list_.HasObserver(observer));
+  Send(new FrameHostMsg_MediaPausedNotification(
+      routing_id(), GetPlayerId(observer), reached_end_of_stream));
+}
+
+void RendererWebMediaPlayerDelegate::PlayerGone(Observer* observer) {
+  DCHECK(observer_list_.HasObserver(observer));
+  Send(new FrameHostMsg_MediaDestroyedNotification(routing_id(),
+                                                   GetPlayerId(observer)));
+}
+
+bool RendererWebMediaPlayerDelegate::IsHidden() {
+  return render_frame()->IsHidden();
+}
+
 void RendererWebMediaPlayerDelegate::WasHidden() {
   FOR_EACH_OBSERVER(Observer, observer_list_, OnHidden());
 }
 
 void RendererWebMediaPlayerDelegate::WasShown() {
   FOR_EACH_OBSERVER(Observer, observer_list_, OnShown());
 }
 
-bool RendererWebMediaPlayerDelegate::IsHidden() {
-  return render_frame()->IsHidden();
+bool RendererWebMediaPlayerDelegate::OnMessageReceived(
+    const IPC::Message& msg) {
+  bool handled = true;
+  IPC_BEGIN_MESSAGE_MAP(RendererWebMediaPlayerDelegate, msg)
+    IPC_MESSAGE_HANDLER(FrameMsg_MediaDelegatePause, OnMediaDelegatePause)
+    IPC_MESSAGE_HANDLER(FrameMsg_MediaDelegatePlay, OnMediaDelegatePlay)
+    IPC_MESSAGE_HANDLER(FrameMsg_MediaDelegateVolumeMultiplierUpdate,
+                        OnMediaDelegateVolumeMultiplierUpdate)
+    IPC_MESSAGE_UNHANDLED(handled = false)
+  IPC_END_MESSAGE_MAP()
+  return handled;
+}
+
+bool RendererWebMediaPlayerDelegate::GetObserver(int64_t player_cookie,
+                                                 Observer** observer) {

[nasko, 2016/01/22 17:28:32]

Wouldn't returning a pointer to the observer be simpler? Looking at the code,
false means there is no observer and true means the output is set.

[DaleCurtis, 2016/01/23 02:11:00]

Done.

+  // Translate the player cookie back to a Observer instance and make sure it's
+  // still a valid instance.
+  Observer* result = reinterpret_cast<Observer*>(player_cookie);

[nasko, 2016/01/22 17:28:32]

Using pointer values for cookies should not be done. It leaks heap layout
information across processes and is not guaranteed uniqueness, especially with
PartitionAlloc. Generating a random number and having a map from it to observer
is better approach.

[DaleCurtis, 2016/01/23 02:11:00]

Done.

+  if (!observer_list_.HasObserver(result))
+    return false;
+
+  *observer = result;
+  return true;
+}
+
+void RendererWebMediaPlayerDelegate::OnMediaDelegatePause(
+    int64_t player_cookie) {
+  Observer* observer;
+  if (GetObserver(player_cookie, &observer))
+    observer->OnPause();
+}
+
+void RendererWebMediaPlayerDelegate::OnMediaDelegatePlay(
+    int64_t player_cookie) {
+  Observer* observer;
+  if (GetObserver(player_cookie, &observer))
+    observer->OnPlay();
+}
+
+void RendererWebMediaPlayerDelegate::OnMediaDelegateVolumeMultiplierUpdate(
+    int64_t player_cookie,
+    double multiplier) {
+  Observer* observer;
+  if (GetObserver(player_cookie, &observer))
+    observer->OnVolumeMultiplierUpdate(multiplier);
 }
 
 }  // namespace media