Add metadata to media::VideoFrame and plumb it through IPC/MediaStream.

media/base/video_frame.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_BASE_VIDEO_FRAME_H_
 #define MEDIA_BASE_VIDEO_FRAME_H_
 
 #include <vector>
 
 #include "base/callback.h"
 #include "base/md5.h"
 #include "base/memory/shared_memory.h"
 #include "base/synchronization/lock.h"
+#include "base/values.h"
 #include "media/base/buffers.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/size.h"
 
 #if defined(OS_MACOSX)
 #include <CoreVideo/CVPixelBuffer.h>
 #include "base/mac/scoped_cftyperef.h"
 #endif
 
 namespace gpu {
@@ skipping 37 matching lines @@
     NATIVE_TEXTURE = 6,  // Native texture.  Pixel-format agnostic.
     YV12J = 7,  // JPEG color range version of YV12
     NV12 = 8,  // 12bpp 1x1 Y plane followed by an interleaved 2x2 UV plane.
     YV24 = 9,  // 24bpp YUV planar, no subsampling.
     ARGB = 10,  // 32bpp ARGB, 1 plane.
     YV12HD = 11,  // Rec709 "HD" color space version of YV12
     // Please update UMA histogram enumeration when adding new formats here.
     FORMAT_MAX = YV12HD,  // Must always be equal to largest entry logged.
   };
 
+  // Key for getting/setting the frame rate value (of type DoubleValue) in the
+  // metadata dictionary.  The value represents either the fixed frame rate, or
+  // the maximum frame rate to expect from a variable-rate source.
+  static const char kFrameRateMetadataKey[];
+
   // Returns the name of a Format as a string.
   static std::string FormatToString(Format format);
 
   // Creates a new frame in system memory with given parameters. Buffers for
   // the frame are allocated but not initialized.
   static scoped_refptr<VideoFrame> CreateFrame(
       Format format,
       const gfx::Size& coded_size,
       const gfx::Rect& visible_rect,
       const gfx::Size& natural_size,
@@ skipping 200 matching lines @@
   // Only valid to call if this is a NATIVE_TEXTURE frame. Before using the
   // mailbox, the caller must wait for the included sync point.
   const gpu::MailboxHolder* mailbox_holder() const;
 
   // Returns the shared-memory handle, if present
   base::SharedMemoryHandle shared_memory_handle() const;
 
   // Returns the offset into the shared memory where the frame data begins.
   size_t shared_memory_offset() const;
 
+  // Returns a dictionary of optional metadata.  This contains information
+  // associated with the frame that downstream clients might use for frame-level
+  // logging, quality/performance optimizations, signaling, etc.
+  //
+  // TODO(miu): Move some of the "extra" members of VideoFrame (below) into
+  // here as a later clean-up step.
+  const base::DictionaryValue& metadata() const { return metadata_; }
+  base::DictionaryValue& metadata() { return metadata_; }
+
   bool allow_overlay() const { return allow_overlay_; }
 
 #if defined(OS_POSIX)
   // Returns backing dmabuf file descriptor for given |plane|, if present.
   int dmabuf_fd(size_t plane) const;
 #endif
 
 #if defined(OS_MACOSX)
   // Returns the backing CVPixelBuffer, if present.
   CVPixelBufferRef cv_pixel_buffer() const;
@@ skipping 95 matching lines @@
 
   base::Closure no_longer_needed_cb_;
 
   base::TimeDelta timestamp_;
 
   base::Lock release_sync_point_lock_;
   uint32 release_sync_point_;
 
   const bool end_of_stream_;
 
+  base::DictionaryValue metadata_;
+
   bool allow_overlay_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(VideoFrame);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_VIDEO_FRAME_H_