Introduce new interface for MediaInternals updates.

content/browser/media/media_internals.h

 // Copyright (c) 2012 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_MEDIA_INTERNALS_H_
 #define CONTENT_BROWSER_MEDIA_MEDIA_INTERNALS_H_
 
 #include <string>
 #include <vector>
 
-#include "base/memory/ref_counted.h"
-#include "base/memory/singleton.h"
+#include "base/callback_forward.h"
+#include "base/lazy_instance.h"
 #include "base/strings/string16.h"
+#include "base/synchronization/lock.h"
 #include "base/values.h"
 #include "content/common/content_export.h"
-#include "content/public/common/media_stream_request.h"
+#include "media/audio/audio_logging.h"
 
 namespace media {
 class AudioParameters;
 struct MediaLogEvent;
 }
 
 namespace content {
 
 // This class stores information about currently active media.
-// It's constructed on the UI thread but all of its methods are called on the IO
-// thread.
-class CONTENT_EXPORT MediaInternals {
+class CONTENT_EXPORT MediaInternals : public media::AudioLogFactory {

[acolwell GONE FROM CHROMIUM, 2013/11/22 21:01:21]

Since this is the only object that derives from AudioLogFactory and the only
call site actually knows it has a MediaInternals object, I wonder of the Factory
interface is really necessary. Are there other cases where the AudioLogFactory
interface would be used? 

[DaleCurtis, 2013/11/22 21:16:03]

Most of the audio code lives in media/ not content/, so in order for
AudioManager and AudioOutputDispatcherImpl, etc to use the code the interface is
necessary.

My current idea is to have BrowserMainLoop pass in an AudioLogFactory to the
AudioManager (or inject one) which all browser side media/ components can access
through a public getter.

  public:
+  static MediaInternals* GetInstance();
+
   virtual ~MediaInternals();
 
-  static MediaInternals* GetInstance();
-
-  // The following methods are virtual for gmock.
-
-  // Called when an audio stream is deleted.
-  virtual void OnDeleteAudioStream(void* host, int stream_id);
-
-  // Called when an audio stream is set to playing or paused.
-  virtual void OnSetAudioStreamPlaying(void* host, int stream_id, bool playing);
-
-  // Called when an audio stream is created with the parameters that
-  // it attempts to use to make the stream.
-  virtual void OnAudioStreamCreated(void* host,
-                                    int stream_id,
-                                    const media::AudioParameters& params,
-                                    const std::string& input_device_id);
-
-  // Called when the status of an audio stream is set to "created", "closed", or
-  // "error".
-  virtual void OnSetAudioStreamStatus(void* host, int stream_id,
-                                      const std::string& status);
-
-  // Called when the volume of an audio stream is set.
-  virtual void OnSetAudioStreamVolume(void* host, int stream_id,
-                                      double volume);
-
   // Called when a MediaEvent occurs.
-  virtual void OnMediaEvents(int render_process_id,
-                             const std::vector<media::MediaLogEvent>& events);
+  void OnMediaEvents(int render_process_id,
+                     const std::vector<media::MediaLogEvent>& events);
 
   // Called with the update string.
   typedef base::Callback<void(const string16&)> UpdateCallback;
 
-  // Add/remove update callbacks (see above).
+  // Add/remove update callbacks (see above).  Must be called on the IO thread.
   void AddUpdateCallback(const UpdateCallback& callback);
   void RemoveUpdateCallback(const UpdateCallback& callback);
+
+  // Sends all cached data to each registered UpdateCallback.
   void SendEverything();
 
+  // AudioLogFactory implementation.  Safe to call from any thread.
+  virtual scoped_ptr<media::AudioLog> CreateAudioLog(
+      AudioComponent component) OVERRIDE;
+
  private:
-  friend class MockMediaInternals;
+  friend class AudioLogImpl;
   friend class MediaInternalsTest;
-  friend struct DefaultSingletonTraits<MediaInternals>;
+  friend struct base::DefaultLazyInstanceTraits<MediaInternals>;
 
   MediaInternals();
 
-  // Sets |property| of an audio stream to |value| and notifies observers.
-  // (host, stream_id) is a unique id for the audio stream.
-  // |host| will never be dereferenced.
-  void UpdateAudioStream(void* host, int stream_id,
-                         const std::string& property, base::Value* value);
+  // Sends |update| to each registered UpdateCallback.  Safe to call from any
+  // thread, but will forward to the IO thread.
+  void SendUpdate(const string16& update);
 
-  // See UpdateAudioStream.  The difference is that StoreAudioStream does not
-  // immediately send the data to the client, instead it waits until
-  // SendEverything is called.
-  void StoreAudioStream(void* host,
-                        int stream_id,
-                        const std::string& property,
-                        base::Value* value);
+  // Caches |value| under |cache_key| so that future SendEverything() calls will
+  // include the current data.  Calls JavaScript |function|(|value|) for each
+  // registered UpdateCallback.  SendUpdateAndPurgeCache() is similar but purges
+  // the cache entry after completion instead.
+  void SendUpdateAndCache(const std::string& cache_key,
+                          const std::string& function,
+                          const base::DictionaryValue* value);
+  void SendUpdateAndPurgeCache(const std::string& cache_key,
+                               const std::string& function,
+                               const base::DictionaryValue* value);
+  // Must only be accessed on the IO thread.
+  std::vector<UpdateCallback> update_callbacks_;
 
-  // Removes |item| from |data_|.
-  void DeleteItem(const std::string& item);
-
-  base::DictionaryValue* StoreItem(const std::string& id,
-                                   const std::string& property,
-                                   base::Value* value);
-
-  // Sets data_.id.property = value and notifies attached UIs using update_fn.
-  // id may be any depth, e.g. "video.decoders.1.2.3"
-  void UpdateItem(const std::string& update_fn, const std::string& id,
-                  const std::string& property, base::Value* value);
-
-  // Calls javascript |function|(|value|) on each attached UI.
-  void SendUpdate(const std::string& function, base::Value* value);
-
-  base::DictionaryValue data_;
-
-  std::vector<UpdateCallback> update_callbacks_;
+  base::Lock cache_lock_;
+  base::DictionaryValue cached_data_;
+  int owner_ids_[AUDIO_COMPONENT_MAX];
 
   DISALLOW_COPY_AND_ASSIGN(MediaInternals);
 };
 
 } // namespace content
 
 #endif  // CONTENT_BROWSER_MEDIA_MEDIA_INTERNALS_H_