Introduce a client minimum picture pool size

media/video/video_decode_accelerator.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_VIDEO_VIDEO_DECODE_ACCELERATOR_H_
 #define MEDIA_VIDEO_VIDEO_DECODE_ACCELERATOR_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
@@ skipping 43 matching lines @@
 
   // Interface for collaborating with picture interface to provide memory for
   // output picture and blitting them. These callbacks will not be made unless
   // Initialize() has returned successfully.
   // This interface is extended by the various layers that relay messages back
   // to the plugin, through the PPP_VideoDecoder_Dev interface the plugin
   // implements.
   class MEDIA_EXPORT Client {
    public:
     // Callback to tell client how many and what size of buffers to provide.
+    // Note that the actual count provided through AssignPictureBuffers() can be
+    // larger than the value requested.
     virtual void ProvidePictureBuffers(uint32 requested_num_of_buffers,
                                        const gfx::Size& dimensions,
                                        uint32 texture_target) = 0;
 
     // Callback to dismiss picture buffer that was assigned earlier.
     virtual void DismissPictureBuffer(int32 picture_buffer_id) = 0;
 
     // Callback to deliver decoded pictures ready to be displayed.
     virtual void PictureReady(const Picture& picture) = 0;
 
@@ skipping 34 matching lines @@
   //  |bitstream_buffer| is the input bitstream that is sent for decoding.
   virtual void Decode(const BitstreamBuffer& bitstream_buffer) = 0;
 
   // Assigns a set of texture-backed picture buffers to the video decoder.
   //
   // Ownership of each picture buffer remains with the client, but the client
   // is not allowed to deallocate the buffer before the DismissPictureBuffer
   // callback has been initiated for a given buffer.
   //
   // Parameters:
-  //  |buffers| contains the allocated picture buffers for the output.
+  //  |buffers| contains the allocated picture buffers for the output.  Note
+  //  that the count of buffers may be larger than the count requested through
+  //  the call to Client::ProvidePictureBuffers().
   virtual void AssignPictureBuffers(
       const std::vector<PictureBuffer>& buffers) = 0;
 
   // Sends picture buffers to be reused by the decoder. This needs to be called
   // for each buffer that has been processed so that decoder may know onto which
   // picture buffers it can write the output to.
   //
   // Parameters:
   //  |picture_buffer_id| id of the picture buffer that is to be reused.
   virtual void ReusePictureBuffer(int32 picture_buffer_id) = 0;
@@ skipping 48 matching lines @@
 // uses "Destroy()" instead of trying to use the destructor.
 template <>
 struct MEDIA_EXPORT DefaultDeleter<media::VideoDecodeAccelerator> {
  public:
   void operator()(void* video_decode_accelerator) const;
 };
 
 }  // namespace base
 
 #endif  // MEDIA_VIDEO_VIDEO_DECODE_ACCELERATOR_H_