cast: Support for low-latency interactive mode

media/base/video_frame_metadata.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 MEDIA_BASE_VIDEO_FRAME_METADATA_H_
 #define MEDIA_BASE_VIDEO_FRAME_METADATA_H_
 
+#include <string>
+
 #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 {
@@ skipping 25 matching lines @@
     // frame-level resource utilization stats.  Use Get/SetTimeDelta() for this
     // key.
     FRAME_DURATION,
 
     // Represents either the fixed frame rate, or the maximum frame rate to
     // expect from a variable-rate source.  This value generally remains the
     // same for all frames in the same session.  Use Get/SetDouble() for this
     // key.
     FRAME_RATE,
 
+    // This is a boolean that signals that the video capture engine detects
+    // interactive content. One possible optimization that this signal can help
+    // with is remote content: adjusting end-to-end latency down to help the
+    // user better coordinate their actions.
+    //
+    // Use Get/SetBoolean for this key.
+    INTERACTIVE_CONTENT,
+
     // This field represents the local time at which either: 1) the frame was
     // generated, if it was done so locally; or 2) the targeted play-out time
     // of the frame, if it was generated from a remote source. This value is NOT
     // a high-resolution timestamp, and so it should not be used as a
     // presentation time; but, instead, it should be used for buffering playback
     // and for A/V synchronization purposes.
     // Use Get/SetTimeTicks() for this key.
     REFERENCE_TIME,
 
     // A feedback signal that indicates the fraction of the tolerable maximum
@@ skipping 55 matching lines @@
   const base::BinaryValue* GetBinaryValue(Key key) const;
 
   base::DictionaryValue dictionary_;
 
   DISALLOW_COPY_AND_ASSIGN(VideoFrameMetadata);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_VIDEO_FRAME_METADATA_H_