Use explicit flush for ArcVideoAccelerator.

chrome/gpu/arc_video_accelerator.h

 // Copyright 2016 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 CHROME_GPU_ARC_VIDEO_ACCELERATOR_H_
 #define CHROME_GPU_ARC_VIDEO_ACCELERATOR_H_
 
 #include "base/files/scoped_file.h"
 
 namespace chromeos {
 namespace arc {
 
 enum HalPixelFormatExtension {
   // The pixel formats defined in Android but are used here. They are defined
   // in "system/core/include/system/graphics.h"
   HAL_PIXEL_FORMAT_YCbCr_420_888 = 0x23,
 
   // The following formats are not defined in Android, but used in
   // ArcVideoAccelerator to identify the input format.
   HAL_PIXEL_FORMAT_H264 = 0x34363248,
   HAL_PIXEL_FORMAT_VP8 = 0x00385056,
 };
 
 enum PortType {
   PORT_INPUT = 0,
   PORT_OUTPUT = 1,
   PORT_COUNT = 2,
 };
 
-enum BufferFlag {
-  BUFFER_FLAG_EOS = 1 << 0,
-};
-
 struct BufferMetadata {
   int64_t timestamp = 0;  // in microseconds
-  uint32_t flags = 0;     // Flags defined in BufferFlag.
+  uint32_t flags = 0;     // Not used.

[dcheng, 2016/05/07 06:18:11]

Why do we need to keep this unused field?

[Owen Lin, 2016/05/09 07:04:41]

Just get a feeling it will be used soon. Let's remove it and add back when we
really need it.

   uint32_t bytes_used = 0;
 };
 
 struct VideoFormat {
   uint32_t pixel_format = 0;
   uint32_t buffer_size = 0;
 
   // Minimum number of buffers required to decode/encode the stream.
   uint32_t min_num_buffers = 0;
   uint32_t coded_width = 0;
@@ skipping 47 matching lines @@
     virtual void OnBufferDone(PortType port,
                               uint32_t index,
                               const BufferMetadata& metadata) = 0;
 
     // Called when the output format has changed or the output format
     // becomes available at beginning of the stream after initial parsing.
     virtual void OnOutputFormatChanged(const VideoFormat& format) = 0;
 
     // Called as a completion notification for Reset().
     virtual void OnResetDone() = 0;
+
+    // Called as a completion notification for Flush().
+    virtual void OnFlushDone() = 0;
   };
 
   // Initializes the ArcVideoAccelerator with specific configuration. This
   // must be called before any other methods. This call is synchronous and
   // returns true iff initialization is successful.
   virtual bool Initialize(const Config& config, Client* client) = 0;
 
   // Assigns a shared memory to be used for the accelerator at the specified
   // port and index. A buffer must be successfully bound before it can be passed
   // to the accelerator via UseBuffer(). Already bound buffers may be reused
@@ skipping 21 matching lines @@
 
   // Sets the number of output buffers. When it fails, Client::OnError() will
   // be called.
   virtual void SetNumberOfOutputBuffers(size_t number) = 0;
 
   // Resets the accelerator. When it is done, Client::OnResetDone() will
   // be called. Afterwards, all buffers won't be accessed by the accelerator
   // and there won't be more callbacks.
   virtual void Reset() = 0;
 
+  // Flushes the accelerator. After all the output buffers have been returned
+  // to client by OnBufferDone(), Client::OnFlushDone() will be called.

[Pawel Osciak, 2016/05/09 07:27:39]

I think this is after all frames pending decode and/or display have been
returned, but not specifically all output buffers (we won't get empty buffers
back)?

[Owen Lin, 2016/05/10 08:26:33]

Comments modified accordingly.

+  virtual void Flush() = 0;
+
   virtual ~ArcVideoAccelerator() {}
 };
 
 }  // namespace arc
 }  // namespace chromeos
 
 #endif  // CHROME_GPU_ARC_VIDEO_ACCELERATOR_H_