Add JPEG decoder for VAAPI JPEG decode acceleration

content/common/gpu/media/vaapi_jpeg_decoder.h

+// Copyright 2015 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 CONTENT_COMMON_GPU_MEDIA_VAAPI_JPEG_DECODER_H_
+#define CONTENT_COMMON_GPU_MEDIA_VAAPI_JPEG_DECODER_H_
+
+#include "base/macros.h"
+#include "content/common/content_export.h"
+#include "content/common/gpu/media/vaapi_wrapper.h"
+
+namespace media {
+struct JpegParseResult;
+}  // namespace media
+
+namespace content {
+
+// A JPEG decoder that utilizes VA-API hardware video decode acceleration on
+// Intel systems. Provides functionality to allow plugging VAAPI HW
+// acceleration into the JDA framework.

[wuchengli, 2015/01/20 07:55:53]

s/JDA/JpegDecodeAccelerator/ It's an uncommon acronym.

[kcwu, 2015/01/21 12:23:48]

Done.

+//
+// Clients of this class are expected to manage VA surfaces created via
+// VaapiWrapper, parse JPEG picture via ParseJpegPicture, and then pass them to

[wuchengli, 2015/01/20 07:55:53]

s/ParseJpegPicture/media::ParseJpegPicture/

[kcwu, 2015/01/21 12:23:48]

Done.

+// this class.
+//
+// This class must be called on a single thread, and does nothing internally on
+// any other thread.
+class CONTENT_EXPORT VaapiJpegDecoder {
+ public:
+  // |vaapi_wrapper| should be initialized in kDecode mode with
+  // VAProfileJPEGBaseline profile.
+  // This class doesn't take the ownership of |vaapi_wrapper|.
+  VaapiJpegDecoder(VaapiWrapper* vaapi_wrapper);
+
+  ~VaapiJpegDecoder();
+
+  // Decode a JPEG picture. It will fill VA-API parameters and call
+  // corresponding VA-API methods according to parsed JPEG result
+  // |parse_result|. Decoded data will be outputted to the given |va_surface|.
+  // Return false on failure.
+  bool Decode(const media::JpegParseResult& parse_result,

[wuchengli, 2015/01/20 15:41:41]

This can be static and pass VaapiWrapper here. It's much more clear
VaapiJpegDecoder is stateless and doesn't own |vaapi_wrapper|. Please also
explain the prerequisite of |va_surface| here. For example, the surface should
be created with the picture size (or >= the picture size?). 

[kcwu, 2015/01/21 12:23:48]

Done.

+              VASurfaceID va_surface);
+
+ private:
+  VaapiWrapper* vaapi_wrapper_;
+
+  DISALLOW_COPY_AND_ASSIGN(VaapiJpegDecoder);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_COMMON_GPU_MEDIA_VAAPI_JPEG_DECODER_H_