Add experimental 'backlog' heuristic for measuring encoder utilization.

media/base/media_switches.cc

Index: media/base/media_switches.cc
diff --git a/media/base/media_switches.cc b/media/base/media_switches.cc
index 846f25e75aa6ee2cabc06eebe3636a30b4736238..348792e43c271501a4b9010c5aeed41da8f6c44e 100644
--- a/media/base/media_switches.cc
+++ b/media/base/media_switches.cc
@@ -123,6 +123,14 @@ const char kDisableRTCSmoothnessAlgorithm[] =
 // if MP4 demuxing is not enabled in the build.
 const char kEnableVp9InMp4[] = "enable-vp9-in-mp4";
 
+// Switches which method is used to compute the encoder utilization metric
+// (e.g., --cast-encoder-util-heuristic=backlog).
+//
+// TODO(miu): This is temporary, for lab performance testing, until a
+// good "works for all" solution is confirmed.
+// https://code.google.com/p/chrome-os-partner/issues/detail?id=54806
+const char kCastEncoderUtilHeuristic[] = "cast-encoder-util-heuristic";
+
 }  // namespace switches
 
 namespace media {