Add support for single sample metrics.

media/renderers/video_renderer_impl.cc

Index: media/renderers/video_renderer_impl.cc
diff --git a/media/renderers/video_renderer_impl.cc b/media/renderers/video_renderer_impl.cc
index d4e660272012a8f480f7527391399000849a080c..1e7f28454cbb8c60d2513bf15d08153dac3a02d5 100644
--- a/media/renderers/video_renderer_impl.cc
+++ b/media/renderers/video_renderer_impl.cc
@@ -11,6 +11,7 @@
 #include "base/callback_helpers.h"
 #include "base/location.h"
 #include "base/metrics/histogram_macros.h"
+#include "base/metrics/single_value_histograms.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/string_util.h"
 #include "base/time/default_tick_clock.h"
@@ -150,6 +151,13 @@ void VideoRendererImpl::Initialize(
   DCHECK(!was_background_rendering_);
   DCHECK(!time_progressing_);
 
+  std::unique_ptr<base::SingleValueCountsHistogram> metric_1(
+      base::SingleValueHistogramsFactory::Get()
+          ->CreateSingleValueCountsHistogram(
+              "Media.VideoRenderer.CadenceChanges", 1, 10, 10));
+  metric_1->SetSample(7);
+  metric_1->SetSample(9);
+
   ScopedVector<VideoDecoder> decoders = create_video_decoders_cb_.Run();
   video_frame_stream_.reset(
       new VideoFrameStream(task_runner_, std::move(decoders), media_log_));