Decouple MediaSession messages from WebContents (full patch)

chromecast/browser/cast_media_blocker.cc

 // 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.
 
 #include "chromecast/browser/cast_media_blocker.h"
 
-#include "base/callback.h"
 #include "base/threading/thread_checker.h"
+#include "content/public/browser/media_session.h"
 #include "content/public/browser/web_contents.h"
 
 namespace chromecast {
 namespace shell {
 
-CastMediaBlocker::CastMediaBlocker(content::WebContents* web_contents)
-    : CastMediaBlocker::CastMediaBlocker(
-          web_contents,
-          base::Bind(&CastMediaBlocker::Suspend, base::Unretained(this)),
-          base::Bind(&CastMediaBlocker::Resume, base::Unretained(this))) {}
-
-CastMediaBlocker::CastMediaBlocker(content::WebContents* web_contents,
-                                   const base::Closure& suspend_cb,
-                                   const base::Closure& resume_cb)
-    : content::WebContentsObserver(web_contents),
-      suspend_cb_(suspend_cb),
-      resume_cb_(resume_cb),
+CastMediaBlocker::CastMediaBlocker(content::MediaSession* media_session,
+                                   content::WebContents* web_contents)
+    : content::MediaSessionObserver(media_session),
+      content::WebContentsObserver(web_contents),
+      media_session_(media_session),
       blocked_(false),
       paused_by_user_(true),
       suspended_(true),
       controllable_(false) {}
 
 CastMediaBlocker::~CastMediaBlocker() {}
 
 void CastMediaBlocker::BlockMediaLoading(bool blocked) {
   if (blocked_ == blocked)
     return;
 
   blocked_ = blocked;
   UpdateMediaBlockedState();
 
   LOG(INFO) << __FUNCTION__ << " blocked=" << blocked_
             << " suspended=" << suspended_ << " controllable=" << controllable_
             << " paused_by_user=" << paused_by_user_;
 
   // If blocking media, suspend if possible.
   if (blocked_) {
     if (!suspended_ && controllable_) {
-      suspend_cb_.Run();
+      Suspend();
     }
     return;
   }
 
   // If unblocking media, resume if media was not paused by user.
   if (!paused_by_user_ && suspended_ && controllable_) {
     paused_by_user_ = true;
-    resume_cb_.Run();
+    Resume();
   }
 }
 
 void CastMediaBlocker::MediaSessionStateChanged(bool is_controllable,
                                                 bool is_suspended) {
   LOG(INFO) << __FUNCTION__ << " blocked=" << blocked_
             << " is_suspended=" << is_suspended
             << " is_controllable=" << is_controllable
             << " paused_by_user=" << paused_by_user_;
 
   // Process controllability first.
   if (controllable_ != is_controllable) {
     controllable_ = is_controllable;
 
     // If not blocked, and we regain control and the media wasn't paused when
     // blocked, resume media if suspended.
     if (!blocked_ && !paused_by_user_ && is_suspended && controllable_) {
       paused_by_user_ = true;
-      resume_cb_.Run();
+      Resume();
     }
 
     // Suspend if blocked and the session becomes controllable.
     if (blocked_ && !is_suspended && controllable_) {
       // Only suspend if suspended_ doesn't change. Otherwise, this will be
       // handled in the suspended changed block.
       if (suspended_ == is_suspended)
-        suspend_cb_.Run();
+        Suspend();
     }
   }
 
   // Process suspended state next.
   if (suspended_ != is_suspended) {
     suspended_ = is_suspended;
     // If blocking, suspend media whenever possible.
     if (blocked_ && !suspended_) {
       // If media was resumed when blocked, the user tried to play music.
       paused_by_user_ = false;
       if (controllable_)
-        suspend_cb_.Run();
+        Suspend();
     }
 
     // If not blocking, cache the user's play intent.
     if (!blocked_)
       paused_by_user_ = suspended_;
   }
 }
 
+void CastMediaBlocker::MediaSessionDestroyed() {
+  media_session_ = nullptr;
+}
+
 void CastMediaBlocker::Suspend() {
-  if (!web_contents())
+  if (!media_session_)
     return;
 
   LOG(INFO) << "Suspending media session.";
-  web_contents()->SuspendMediaSession();
+  media_session_->Suspend(content::MediaSession::SuspendType::SYSTEM);
 }
 
 void CastMediaBlocker::Resume() {
-  if (!web_contents())
+  if (!media_session_)
     return;
 
   LOG(INFO) << "Resuming media session.";
-  web_contents()->ResumeMediaSession();
+  media_session_->Resume(content::MediaSession::SuspendType::SYSTEM);
 }
 
 }  // namespace shell
 }  // namespace chromecast