Add support for single sample metrics.

media/filters/video_cadence_estimator.cc

Index: media/filters/video_cadence_estimator.cc
diff --git a/media/filters/video_cadence_estimator.cc b/media/filters/video_cadence_estimator.cc
index 7548b8277051a0d9e9b659aeb1ca75947d1d2ce7..f5a29bf6be4a13809c598805fe96ec0a2f32be81 100644
--- a/media/filters/video_cadence_estimator.cc
+++ b/media/filters/video_cadence_estimator.cc
@@ -29,10 +29,10 @@ const double kConstantFPSFactor = 0.45;
 
 // Records the number of cadence changes to UMA.
 static void HistogramCadenceChangeCount(int cadence_changes) {
-  const int kCadenceChangeMax = 10;
-  UMA_HISTOGRAM_CUSTOM_COUNTS("Media.VideoRenderer.CadenceChanges",
-                              cadence_changes, 1, kCadenceChangeMax,
-                              kCadenceChangeMax);
+  // const int kCadenceChangeMax = 10;
+  // UMA_HISTOGRAM_CUSTOM_COUNTS("Media.VideoRenderer.CadenceChanges",
+  //                             cadence_changes, 1, kCadenceChangeMax,
+  //                             kCadenceChangeMax);
 }
 
 // Construct a Cadence vector, a vector of integers satisfying the following