Enable fire-and-forget Destroy of HW video decoder, and misc other improvements.

media/video/video_decode_accelerator.h

 // Copyright (c) 2011 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 143 matching lines @@
 enum VideoColorFormat {
   // Value represents 32-bit RGBA format where each component is 8-bit in order
   // R-G-B-A. Regardless of endianness of the architecture color components are
   // stored in this order in the memory.
   VIDEOCOLORFORMAT_RGBA = 0,
 };
 
 // Video decoder interface.
 // This interface is extended by the various components that ultimately
 // implement the backend of PPB_VideoDecode_Dev.
-class VideoDecodeAccelerator {
+//
+// No thread-safety guarantees are implied by the use of RefCountedThreadSafe
+// below.
+class VideoDecodeAccelerator
+    : public base::RefCountedThreadSafe<VideoDecodeAccelerator> {
  public:
-  virtual ~VideoDecodeAccelerator();
-
   // Enumeration of potential errors generated by the API.
   // TODO(fischman): these errors are a bad match for both what OMX generates
   // and for what the plugin wants.  Overhaul this list with a more useful set.
   enum Error {
     VIDEODECODERERROR_NONE = 0,
     VIDEODECODERERROR_UNINITIALIZED,
     VIDEODECODERERROR_UNSUPPORTED,
     VIDEODECODERERROR_INVALIDINPUT,
     VIDEODECODERERROR_MEMFAILURE,
     VIDEODECODERERROR_INSUFFICIENT_BUFFERS,
@@ skipping 41 matching lines @@
     // Callback to notify that decoded has decoded the end of the current
     // bitstream buffer.
     virtual void NotifyEndOfBitstreamBuffer(int32 bitstream_buffer_id) = 0;
 
     // Flush completion callback.
     virtual void NotifyFlushDone() = 0;
 
     // Reset completion callback.
     virtual void NotifyResetDone() = 0;
 
-    // Destroy completion callback.
-    virtual void NotifyDestroyDone() = 0;
-
     // Callback to notify about decoding errors.
     virtual void NotifyError(Error error) = 0;
   };
 
   // Video decoder functions.
 
   // Initializes the video decoder with specific configuration.
   // Parameters:
   //  |config| is the configuration on which the decoder should be initialized.
   //
@@ skipping 30 matching lines @@
   // client.  Can be used to implement "end of stream" notification.
   virtual void Flush() = 0;
 
   // Resets the decoder: all pending inputs are dropped immediately and the
   // decoder returned to a state ready for further Decode()s, followed by
   // NotifyResetDone() being called on the client.  Can be used to implement
   // "seek".
   virtual void Reset() = 0;
 
   // Destroys the decoder: all pending inputs are dropped immediately and the
-  // component is freed, followed by NotifyDestroyDone being called on the
-  // client.  After this is called no other calls may be made on the decoder,
-  // and after NotifyDestroyDone is called no callbacks will be made by the
-  // decoder on the client.
+  // component is freed.  This call may asynchornously free system resources,
+  // but its client-visible effects are synchronous.  After this method returns
+  // no more callbacks will be made on the client.
   virtual void Destroy() = 0;
+
+ protected:
+  friend class base::RefCountedThreadSafe<VideoDecodeAccelerator>;
+  virtual ~VideoDecodeAccelerator();
 };
 
 }  // namespace media
 
 #endif  // MEDIA_VIDEO_VIDEO_DECODE_ACCELERATOR_H_