Implement Audio Focus Manager for desktop.

content/browser/media/session/media_session_delegate_default.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 "content/browser/media/session/media_session_delegate.h"
 
 #include "base/command_line.h"
-#include "content/browser/web_contents/web_contents_impl.h"
+#include "content/browser/media/session/audio_focus_manager.h"
 #include "media/base/media_switches.h"
 
 namespace content {
 
+using AudioFocusType = AudioFocusManager::AudioFocusType;
+
 namespace {
 
 // MediaSessionDelegateDefault is the default implementation of
 // MediaSessionDelegate which only handles audio focus between WebContents.
 class MediaSessionDelegateDefault : public MediaSessionDelegate {
  public:
   explicit MediaSessionDelegateDefault(MediaSession* media_session);
 
   // MediaSessionDelegate implementation.
   bool RequestAudioFocus(MediaSession::Type type) override;
   void AbandonAudioFocus() override;
 
  private:
   // Weak pointer because |this| is owned by |media_session_|.
   MediaSession* media_session_;
 };
 
 }  // anonymous namespace
 
 MediaSessionDelegateDefault::MediaSessionDelegateDefault(
     MediaSession* media_session)
     : media_session_(media_session) {
 }
 
-bool MediaSessionDelegateDefault::RequestAudioFocus(MediaSession::Type) {
+bool MediaSessionDelegateDefault::RequestAudioFocus(MediaSession::Type type) {
   if (!base::CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kEnableDefaultMediaSession)) {
     return true;
   }
 
-  for (WebContentsImpl* web_contents : WebContentsImpl::GetAllWebContents()) {
-    MediaSession* media_session = MediaSession::Get(web_contents);
-    if (media_session == media_session_ || !media_session->IsActive())
-      continue;
-    media_session->Suspend(MediaSession::SuspendType::SYSTEM);
-  }
+  AudioFocusManager::GetInstance()->RequestAudioFocus(
+      media_session_, type == MediaSession::Type::Content
+                          ? AudioFocusType::Gain
+                          : AudioFocusType::GainTransientMayDuck);
   return true;
 }
 
 void MediaSessionDelegateDefault::AbandonAudioFocus() {
+  AudioFocusManager::GetInstance()->AbandonAudioFocus(media_session_);
 }
 
 // static
 std::unique_ptr<MediaSessionDelegate> MediaSessionDelegate::Create(
     MediaSession* media_session) {
   return std::unique_ptr<MediaSessionDelegate>(
       new MediaSessionDelegateDefault(media_session));
 }
 
 }  // namespace content