RESOURCE_UTILIZATION in VideoFrameMetadata, a consumer feedback signal.

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
index b74367a8ef5a473b77a8f935494503826c037468..10b17be087400a4f1193236b7909dafbc19bccca 100644
--- a/media/base/video_frame_metadata.h
+++ b/media/base/video_frame_metadata.h
@@ -43,6 +43,24 @@ class MEDIA_EXPORT VideoFrameMetadata {
     // key.
     FRAME_RATE,
 
+    // A feedback signal that indicates the fraction of the tolerable maximum
+    // amount of resources that were utilized to process this frame.  A producer
+    // can check this value after-the-fact, usually via a VideoFrame destruction
+    // observer, to determine whether the consumer can handle more or less data
+    // volume, and achieve the right quality versus performance trade-off.
+    //
+    // Use Get/SetDouble() for this key.  Values are interpreted as follows:
+    // Less than 0.0 is meaningless and should be ignored.  1.0 indicates a
+    // maximum sustainable utilization.  Greater than 1.0 indicates the consumer
+    // is likely to stall or drop frames if the data volume is not reduced.
+    //
+    // Example: In a system that encodes and transmits video frames over the
+    // network, this value can be used to indicate whether sufficient CPU
+    // is available for encoding and/or sufficient bandwidth is available for
+    // transmission over the network.  The maximum of the two utilization
+    // measurements would be used as feedback.
+    RESOURCE_UTILIZATION,
+
     NUM_KEYS
   };