Add support for single sample metrics.

content/renderer/media/render_media_log.cc

Index: content/renderer/media/render_media_log.cc
diff --git a/content/renderer/media/render_media_log.cc b/content/renderer/media/render_media_log.cc
index 66708ecf115f8c1c548d8b8d28eeed807a0c45fc..69703c7dba1f55b8763aefa345beb0258fa84c8e 100644
--- a/content/renderer/media/render_media_log.cc
+++ b/content/renderer/media/render_media_log.cc
@@ -9,11 +9,13 @@
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/logging.h"
+#include "base/metrics/single_value_histograms.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/time/default_tick_clock.h"
 #include "content/common/view_messages.h"
 #include "content/public/common/content_client.h"
+#include "content/public/common/service_names.mojom.h"
 #include "content/public/renderer/content_renderer_client.h"
 #include "content/public/renderer/render_thread.h"
 
@@ -51,6 +53,21 @@ RenderMediaLog::RenderMediaLog(const GURL& security_origin)
       weak_factory_(this) {
   DCHECK(RenderThread::Get())
       << "RenderMediaLog must be constructed on the render thread";
+
+  std::unique_ptr<base::SingleValueCountsHistogram> metric_1(
+      base::SingleValueHistogramsFactory::Get()
+          ->CreateSingleValueCountsHistogram(
+              "Media.VideoRenderer.CadenceChanges", 1, 10, 10));
+  metric_1->SetSample(3);
+  metric_1->SetSample(2);
+
+  std::unique_ptr<base::SingleValueCountsHistogram> metric_2(
+      base::SingleValueHistogramsFactory::Get()
+          ->CreateSingleValueCountsHistogram(
+              "Media.VideoRenderer.CadenceChanges", 1, 10, 10));
+  metric_2->SetSample(5);
+  metric_2->SetSample(8);
+
   // Pre-bind the WeakPtr on the right thread since we'll receive calls from
   // other threads and don't want races.
   weak_this_ = weak_factory_.GetWeakPtr();