Add video-rendering to mojo media pipeline.

media/base/pipeline.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 MEDIA_BASE_PIPELINE_H_
 #define MEDIA_BASE_PIPELINE_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/time/time.h"
 #include "media/base/buffering_state.h"
@@ skipping 36 matching lines @@
   // The following permanent callbacks will be executed as follows up until
   // Stop() has completed:
   //   |ended_cb| will be executed whenever the media reaches the end.
   //   |error_cb| will be executed whenever an error occurs but hasn't been
   //              reported already through another callback.
   //   |metadata_cb| will be executed when the content duration, container video
   //                 size, start time, and whether the content has audio and/or
   //                 video in supported formats are known.
   //   |buffering_state_cb| will be executed whenever there are changes in the
   //                        overall buffering state of the pipeline.
+  //   |natural_size_changed_cb| will be executed whenever video natural size
+  //                             changes.

[xhwang, 2016/04/12 19:40:37]

Will this be called for the first frame? I feel calling it for the first frame
makes sense because we have a new size). I don't remember what's the historical
magic around the first frame though.

+dalecurtis

[DaleCurtis, 2016/04/12 20:52:42]

The VideoFrameCompositor wants this called for the first frame, without this
Blink may not have the right size information IIRC.

   //   |duration_change_cb| optional callback that will be executed whenever the
   //                        presentation duration changes.
   //   |add_text_track_cb| will be executed whenever a text track is added.
   //   |waiting_for_decryption_key_cb| will be executed whenever the key needed
   //                                   to decrypt the stream is not available.
   // It is an error to call this method after the pipeline has already started.
   virtual void Start(Demuxer* demuxer,
                      scoped_ptr<Renderer> renderer,
                      const base::Closure& ended_cb,
                      const PipelineStatusCB& error_cb,
                      const PipelineStatusCB& seek_cb,
                      const PipelineMetadataCB& metadata_cb,
                      const BufferingStateCB& buffering_state_cb,
+                     const NaturalSizeChangedCB& natural_size_changed_cb,
                      const base::Closure& duration_change_cb,
                      const AddTextTrackCB& add_text_track_cb,
                      const base::Closure& waiting_for_decryption_key_cb) = 0;
 
   // Asynchronously stops the pipeline, executing |stop_cb| when the pipeline
   // teardown has completed.
   //
   // Stop() must complete before destroying the pipeline. It it permissible to
   // call Stop() at any point during the lifetime of the pipeline.
   //
@@ skipping 73 matching lines @@
   // Gets the current pipeline statistics.
   virtual PipelineStatistics GetStatistics() const = 0;
 
   virtual void SetCdm(CdmContext* cdm_context,
                       const CdmAttachedCB& cdm_attached_cb) = 0;
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_PIPELINE_H_