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

media/base/video_frame_metadata.h

Index: media/base/video_frame_metadata.h
diff --git a/media/base/video_frame_metadata.h b/media/base/video_frame_metadata.h
new file mode 100644
index 0000000000000000000000000000000000000000..31fbe74989253c92dab9dd0adc082a8223b2aa2d
--- /dev/null
+++ b/media/base/video_frame_metadata.h
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+// 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 MEDIA_BASE_VIDEO_FRAME_METADATA_H_
+#define MEDIA_BASE_VIDEO_FRAME_METADATA_H_
+
+#include "base/compiler_specific.h"
+#include "base/time/time.h"
+#include "base/values.h"
+#include "media/base/media_export.h"
+
+namespace media {
+
+class MEDIA_EXPORT VideoFrameMetadata {
+ public:
+  enum Key {
+    // Video capture begin/end timestamps.  Consumers can use these values for
+    // dynamic optimizations, logging stats, etc.  Use Get/SetTimeTicks() for
+    // these keys.
+    CAPTURE_BEGIN_TIME,
+    CAPTURE_END_TIME,
+
+    // Represents either the fixed frame rate, or the maximum frame rate to
+    // expect from a variable-rate source.  Use Get/SetDouble() for this key.
+    FRAME_RATE,
+
+    NUM_KEYS
+  };
+
+  VideoFrameMetadata();
+  ~VideoFrameMetadata();
+
+  bool HasKey(Key key) const;
+
+  void Clear() { dictionary_.Clear(); }
+
+  // Setters.  Overwrites existing value, if present.
+  void SetBoolean(Key key, bool value);
+  void SetInteger(Key key, int value);
+  void SetDouble(Key key, double value);
+  void SetString(Key key, const std::string& value);
+  void SetTimeTicks(Key key, const base::TimeTicks& value);
+  void SetValue(Key key, scoped_ptr<base::Value> value);
+
+  // Getters.  Returns true if |key| was present and has the value has been set.
+  bool GetBoolean(Key key, bool* value) const WARN_UNUSED_RESULT;
+  bool GetInteger(Key key, int* value) const WARN_UNUSED_RESULT;
+  bool GetDouble(Key key, double* value) const WARN_UNUSED_RESULT;
+  bool GetString(Key key, std::string* value) const WARN_UNUSED_RESULT;
+  bool GetTimeTicks(Key key, base::TimeTicks* value) const WARN_UNUSED_RESULT;
+
+  // Returns null if |key| was not present.
+  const base::Value* GetValue(Key key) const WARN_UNUSED_RESULT;
+
+  // For serialization.
+  void MergeInternalValuesInto(base::DictionaryValue* out) const;
+  void MergeInternalValuesFrom(const base::DictionaryValue& in);
+
+ private:
+  const base::BinaryValue* GetBinaryValue(Key key) const;
+
+  base::DictionaryValue dictionary_;
+
+  DISALLOW_COPY_AND_ASSIGN(VideoFrameMetadata);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_VIDEO_FRAME_METADATA_H_