Letting Flash join MediaSession (stack implementaion)

content/browser/media/session/media_session.h

 // 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.
 
 #ifndef CONTENT_BROWSER_MEDIA_SESSION_MEDIA_SESSION_H_
 #define CONTENT_BROWSER_MEDIA_SESSION_MEDIA_SESSION_H_
 
 #include <stddef.h>
 
 #include "base/callback_list.h"
@@ skipping 40 matching lines @@
  public:
   enum class SuspendType {
     // Suspended by the system because a transient sound needs to be played.
     SYSTEM,
     // Suspended by the UI.
     UI,
     // Suspended by the page via script or user interaction.
     CONTENT,
   };
 
+  // Only visible to tests.
+  enum class State {
+    ACTIVE,
+    SUSPENDED,
+    INACTIVE
+  };
+
   // Returns the MediaSession associated to this WebContents. Creates one if
   // none is currently available.
   CONTENT_EXPORT static MediaSession* Get(WebContents* web_contents);
 
   ~MediaSession() override;
 
   void SetMetadata(const base::Optional<MediaMetadata>& metadata);
   const base::Optional<MediaMetadata>& metadata() const { return metadata_; }
 
   // Adds the given player to the current media session. Returns whether the
@@ skipping 46 matching lines @@
   CONTENT_EXPORT bool IsControllable() const;
 
   // Returns if the session is currently active.
   CONTENT_EXPORT bool IsActive() const;
 
   // Returns if the session is currently suspended.
   // TODO(mlamouri): IsSuspended() below checks if the state is not ACTIVE
   // instead of checking if the state is SUSPENDED. In order to not have to
   // change all the callers and make the current refactoring ridiculously huge,
   // this method is introduced temporarily and will be removed later.
-  bool IsReallySuspended() const;
+  CONTENT_EXPORT bool IsReallySuspended() const;
 
   // Returns if the session is currently suspended or inactive.
   CONTENT_EXPORT bool IsSuspended() const;
 
+  // Returns the audio focus type. The type is updated everytime after the
+  // session requests audio focus.
+  CONTENT_EXPORT AudioFocusManager::AudioFocusType audio_focus_type() const {

[mlamouri (slow - plz ping), 2016/09/30 09:35:22]

Can we keep this private?

[Zhiqiang Zhang (Slow), 2016/09/30 10:04:42]

No, it is used by AudioFocusManager

+    return audio_focus_type_;
+  }
+
+  void WebContentsDestroyed() override;

[mlamouri (slow - plz ping), 2016/09/30 09:35:22]

ditto

[Zhiqiang Zhang (Slow), 2016/09/30 10:04:42]

It's overriding a public method from WebContentsObserver. I prefer to keep it
public, though it not directly called anywhere.

+
+  // Returns whether the session has Pepper instances.
+  bool HasPepper() const;
+
  private:
   friend class content::WebContentsUserData<MediaSession>;
   friend class ::MediaSessionBrowserTest;
   friend class content::MediaSessionVisibilityBrowserTest;
   friend class content::AudioFocusManagerTest;
   friend class content::MediaSessionStateObserver;
 
   CONTENT_EXPORT void SetDelegateForTests(
       std::unique_ptr<MediaSessionDelegate> delegate);
   CONTENT_EXPORT bool IsActiveForTest() const;
-  CONTENT_EXPORT AudioFocusManager::AudioFocusType audio_focus_type_for_test()
-      const;
   CONTENT_EXPORT void RemoveAllPlayersForTest();
   CONTENT_EXPORT MediaSessionUmaHelper* uma_helper_for_test();
 
-  enum class State {
-    ACTIVE,
-    SUSPENDED,
-    INACTIVE
-  };
-
   // Representation of a player for the MediaSession.
   struct PlayerIdentifier {
     PlayerIdentifier(MediaSessionObserver* observer, int player_id);
     PlayerIdentifier(const PlayerIdentifier&) = default;
 
     void operator=(const PlayerIdentifier&) = delete;
     bool operator==(const PlayerIdentifier& player_identifier) const;
 
     // Hash operator for base::hash_map<>.
     struct Hash {
       size_t operator()(const PlayerIdentifier& player_identifier) const;
     };
 
     MediaSessionObserver* observer;
     int player_id;
   };
   using PlayersMap = base::hash_set<PlayerIdentifier, PlayerIdentifier::Hash>;
   using StateChangedCallback = base::Callback<void(State)>;
 
   CONTENT_EXPORT explicit MediaSession(WebContents* web_contents);
 
   void Initialize();
 
   CONTENT_EXPORT void OnSuspendInternal(SuspendType suspend_type,
                                         State new_state);
   CONTENT_EXPORT void OnResumeInternal(SuspendType suspend_type);
 
   // Requests audio focus to the MediaSessionDelegate.
   // Returns whether the request was granted.
-  bool RequestSystemAudioFocus(
+  CONTENT_EXPORT bool RequestSystemAudioFocus(
       AudioFocusManager::AudioFocusType audio_focus_type);
 
   // To be called after a call to AbandonAudioFocus() in order request the
   // delegate to abandon the audio focus.
-  void AbandonSystemAudioFocusIfNeeded();
+  CONTENT_EXPORT void AbandonSystemAudioFocusIfNeeded();
 
   // Notifies WebContents about the state change of the media session.
   void UpdateWebContents();
 
   // Internal method that should be used instead of setting audio_focus_state_.
   // It sets audio_focus_state_ and notifies observers about the state change.
   void SetAudioFocusState(State audio_focus_state);
 
   // Update the volume multiplier when ducking state changes.
   void UpdateVolumeMultiplier();
 
   // Get the volume multiplier, which depends on whether the media session is
   // ducking.
   double GetVolumeMultiplier() const;
 
   // Registers a MediaSession state change callback.
   CONTENT_EXPORT std::unique_ptr<base::CallbackList<void(State)>::Subscription>
   RegisterMediaSessionStateChangedCallbackForTest(
       const StateChangedCallback& cb);
 
+  CONTENT_EXPORT bool AddPepperPlayer(MediaSessionObserver* observer,
+                                      int player_id);
+
   std::unique_ptr<MediaSessionDelegate> delegate_;
   PlayersMap players_;
+  PlayersMap pepper_players_;
 
   State audio_focus_state_;
   SuspendType suspend_type_;
   AudioFocusManager::AudioFocusType audio_focus_type_;
 
   MediaSessionUmaHelper uma_helper_;
 
   // The ducking state of this media session. The initial value is |false|, and
   // is set to |true| after StartDucking(), and will be set to |false| after
   // StopDucking().
   bool is_ducking_;
 
   base::Optional<MediaMetadata> metadata_;
   base::CallbackList<void(State)> media_session_state_listeners_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaSession);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_MEDIA_SESSION_MEDIA_SESSION_H_