Add Mojo interfaces for GpuJpegDecodeAccelerator and GpuJpegDecodeAcceleratorHost

media/gpu/mojo/jpeg_decoder.mojom

+// Copyright 2017 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.
+
+module media.mojom;
+
+import "media/mojo/interfaces/media_types.mojom";
+import "ui/gfx/geometry/mojo/geometry.mojom";
+
+enum Error {
+  NO_ERRORS,
+  INVALID_ARGUMENT,
+  UNREADABLE_INPUT,
+  PARSE_JPEG_FAILED,
+  UNSUPPORTED_JPEG,
+  PLATFORM_FAILURE,
+};
+
+struct JpegDecodeInfo {
+  BitstreamBuffer input_buffer;
+  gfx.mojom.Size coded_size;
+  handle<shared_buffer> output_handle;
+  uint32 output_buffer_size;
+};
+
+interface GpuJpegDecodeAcceleratorClient {
+  // Report decode status.
+  OnDecodeAck(int32 bitstream_buffer_id, Error error);
+};
+
+// Initialize() must be called before using Decode().
+interface GpuJpegDecodeAccelerator {

[xhwang, 2017/06/01 05:17:19]

Depending on how this interface interacts with GpuJpegDecodeAcceleratorClient
interface, you might want to use associated interfaces:

https://www.chromium.org/developers/design-documents/mojo/associated-interfaces

[Chandan, 2017/06/01 05:54:26]

GpuJpegDecodeAccelerator will use GpuJpegDecodeAcceleratorClient only to make
the OnDecodeAck() call. Do we need to use associated interfaces for this?

+  Initialize(GpuJpegDecodeAcceleratorClient client) => (bool success);
+
+  // Decode one JPEG image from shared memory |input_buffer_handle| with size
+  // |input_buffer_size|. The input buffer is associated with |input_buffer_id|
+  // and the size of JPEG image is |coded_size|. Decoded I420 frame data will

[xhwang, 2017/06/01 05:17:19]

These seem to belong to line 18.

[Chandan, 2017/06/01 05:54:25]

May be I need to rename these fields here similar to those in JpegDecodeInfo
above.

[Chandan, 2017/06/01 05:54:26]

I have mapped the existing browser to gpu IPC messages with interface methods of
GpuJpegDecodeAccelerator as it is for now. Borrowed this comment from
https://cs.chromium.org/chromium/src/media/gpu/ipc/common/media_messages.h?l=220.

+  // be put onto shared memory associated with |output_video_frame_handle|

[xhwang, 2017/06/01 05:17:19]

|output_video_frame_handle| not defined anywhere, do you mean |output_handle|?

+  // with size limit |output_buffer_size|.
+  Decode(JpegDecodeInfo info);

[xhwang, 2017/06/01 05:17:19]

Is it a one-to-one mapping between Decode() and OnDecodeAck()? If so, we should
use a callback. If not, it might worth a comment about the relation between the
two.

[Chandan, 2017/06/01 05:54:26]

Decode() and OnDecodeAck() are seperate calls, each one mapped to an existing
IPC message. Please refer
https://cs.chromium.org/chromium/src/media/gpu/ipc/common/media_messages.h?l=220

+
+  // TODO(c.padhi): This method might not be required, see
+  // http://crbug.com/699255.
+  Uninitialize();
+};