Letting Flash join MediaSession (stack implementaion)

content/browser/media/session/audio_focus_manager.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 CONTENT_BROWSER_MEDIA_SESSION_AUDIO_FOCUS_MANAGER_H_
 #define CONTENT_BROWSER_MEDIA_SESSION_AUDIO_FOCUS_MANAGER_H_
 
+#include <list>
 #include <unordered_map>
 
 #include "base/memory/singleton.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/web_contents_observer.h"
 
 namespace content {
 
 class MediaSession;
 class WebContents;
@@ skipping 35 matching lines @@
     AudioFocusType type_;
 
     DISALLOW_COPY_AND_ASSIGN(AudioFocusEntry);
   };
 
   AudioFocusManager();
   ~AudioFocusManager();
 
   void OnWebContentsDestroyed(WebContents* web_contents);
 
-  // Internal usage of AbandonAudioFocus using WebContents.
-  void AbandonAudioFocusInternal(WebContents* web_contents);
-
-  // This method is meant to be called when a new session is of type
-  // GainTransientMayDuck. If it is the first one, other clients will be asked
-  // to duck.
-  void MaybeStartDucking() const;
-
-  // This method is meant to be called when a session is no longer of type
-  // GainTransientMayDuck. If it was the last one, other clients will be asked
-  // to no longer duck.
-  void MaybeStopDucking() const;
-
-  // Returns how many sessions require current audio focused session to duck.
-  int TransientMayDuckEntriesCount() const;
-
-  // Internal method to request audio focus of type AudioFocusType::Gain.
-  void RequestAudioFocusGain(WebContents* web_contents);
-
-  // Removes the entry associated with |web_contents| from the
-  // |transient_entries_| if there is one.
-  void MaybeRemoveTransientEntry(WebContents* web_contents);
-
-  // Removes the focused session if it is associated with |web_contents|.
   void MaybeRemoveFocusEntry(WebContents* web_contents);
 
-  std::unordered_map<WebContents*, std::unique_ptr<AudioFocusEntry>>
-      transient_entries_;
-  std::unique_ptr<AudioFocusEntry> focus_entry_;
+  std::list<std::unique_ptr<AudioFocusEntry>> audio_focus_stack_;

[whywhat, 2016/08/30 21:09:37]

nit: why not std::stack if it is a stack? why call it a stack if it's not
otherwise?

[Zhiqiang Zhang (Slow), 2016/08/31 14:37:34]

I think it is better to use an linked-list implementation for the stack, since
we may remove entries in the middle. WDYT?

[whywhat, 2016/08/31 18:37:09]

That's why I posted a second question. If you use the name stack and the code
uses other than stack behavior of the container, it should be called something
else to avoid confusion. Do we have a description of how this no-so-much-a-stack
works documented somewhere? It's not really easy to grasp from this CL.

 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_MEDIA_SESSION_AUDIO_FOCUS_MANAGER_H_