media: Add UMA to record time to GenerateRequest and LoadSession

media/blink/cdm_result_promise_helper.cc

Index: media/blink/cdm_result_promise_helper.cc
diff --git a/media/blink/cdm_result_promise_helper.cc b/media/blink/cdm_result_promise_helper.cc
index 6c4f9effaae4363c726b156d27adf7fd2943d4e2..a6ae0311c35501f8af0bbab7e27eb60924c57365 100644
--- a/media/blink/cdm_result_promise_helper.cc
+++ b/media/blink/cdm_result_promise_helper.cc
@@ -70,4 +70,14 @@ void ReportCdmResultUMA(const std::string& uma_name, CdmResultForUMA result) {
       base::HistogramBase::kUmaTargetedHistogramFlag)->Add(result);
 }
 
+void ReportTimeUMA(const std::string& uma_name, base::TimeDelta time) {
+  // Note: This leaks memory, which is expected behavior.
+  base::HistogramBase* histogram = base::Histogram::FactoryTimeGet(
+      uma_name, base::TimeDelta::FromMilliseconds(1),
+      base::TimeDelta::FromSeconds(10), 50,
+      base::HistogramBase::kUmaTargetedHistogramFlag);
+
+  histogram->AddTime(time);

[Ilya Sherman, 2017/02/11 00:50:53]

Please use "base::UmaHistogramTimes(name, time);" here.

[xhwang, 2017/02/11 01:12:45]

Great. Didn't know this existed. PTAL again!

+}
+
 }  // namespace media