[Media Router WebUI] Add a UMA metric to record sink search outcome

Add a boolean metric MediaRouter.Sink.SearchOutcome, which records
whether or not a sink was found for the ID that the user entered and
attempted to cast to.

Bug: 867086
Change-Id: Ie1bf8072b7700298b8a783480b05a2e845666946
Reviewed-on: https://chromium-review.googlesource.com/1148956Reviewed-by: Derek Cheng <imcheng@chromium.org>
Reviewed-by: Mark Pearson <mpearson@chromium.org>
Commit-Queue: Takumi Fujimoto <takumif@chromium.org>
Cr-Commit-Position: refs/heads/master@{#578721}

chrome/browser/media/router/media_router_metrics.cc

@@ -61,6 +61,8 @@ const char MediaRouterMetrics::kHistogramMediaSinkType[] =
     "MediaRouter.Sink.SelectedType";
 const char MediaRouterMetrics::kHistogramPresentationUrlType[] =
     "MediaRouter.PresentationRequest.AvailabilityUrlType";
+const char MediaRouterMetrics::kHistogramRecordSearchSinkOutcome[] =
+    "MediaRouter.Sink.SearchOutcome";
 const char MediaRouterMetrics::kHistogramRouteCreationOutcome[] =
     "MediaRouter.Route.CreationOutcome";
 const char MediaRouterMetrics::kHistogramStartLocalLatency[] =
@@ -187,4 +189,9 @@ void MediaRouterMetrics::RecordStartLocalSessionSuccessful(bool success) {
   UMA_HISTOGRAM_BOOLEAN(kHistogramStartLocalSessionSuccessful, success);
 }
 
+// static
+void MediaRouterMetrics::RecordSearchSinkOutcome(bool success) {
+  UMA_HISTOGRAM_BOOLEAN(kHistogramRecordSearchSinkOutcome, success);
+}
+
 }  // namespace media_router

chrome/browser/media/router/media_router_metrics.h

@@ -89,6 +89,7 @@ class MediaRouterMetrics {
   static const char kHistogramMediaRouterFileSize[];
   static const char kHistogramMediaSinkType[];
   static const char kHistogramPresentationUrlType[];
+  static const char kHistogramRecordSearchSinkOutcome[];
   static const char kHistogramRouteCreationOutcome[];
   static const char kHistogramStartLocalLatency[];
   static const char kHistogramStartLocalPosition[];
@@ -159,6 +160,10 @@ class MediaRouterMetrics {
 
   // Records whether or not an attempt to start casting was successful.
   static void RecordStartLocalSessionSuccessful(bool success);
+
+  // Records whether or not a sink was found for the ID that the user manually
+  // entered and attempted to cast to.
+  static void RecordSearchSinkOutcome(bool success);
 };
 
 }  // namespace media_router

chrome/browser/media/router/media_router_metrics_unittest.cc

@@ -38,6 +38,22 @@ void TestRecordTimeDeltaMetric(
   tester.ExpectUniqueSample(histogram_name, delta.InMilliseconds(), 1);
 }
 
+// Tests that calling |recording_cb| with boolean values records them in
+// |histogram_name|.
+void TestRecordBooleanMetric(base::RepeatingCallback<void(bool)> recording_cb,
+                             const std::string& histogram_name) {
+  base::HistogramTester tester;
+  tester.ExpectTotalCount(histogram_name, 0);
+
+  recording_cb.Run(true);
+  recording_cb.Run(false);
+  recording_cb.Run(true);
+
+  tester.ExpectTotalCount(histogram_name, 3);
+  EXPECT_THAT(tester.GetAllSamples(histogram_name),
+              ElementsAre(Bucket(false, 1), Bucket(true, 2)));
+}
+
 }  // namespace
 
 using DialParsingError = SafeDialDeviceDescriptionParser::ParsingError;
@@ -237,19 +253,16 @@ TEST(MediaRouterMetricsTest, RecordStartLocalSessionLatency) {
 }
 
 TEST(MediaRouterMetricsTest, RecordStartLocalSessionSuccessful) {
-  base::HistogramTester tester;
-  tester.ExpectTotalCount(
-      MediaRouterMetrics::kHistogramStartLocalSessionSuccessful, 0);
-
-  MediaRouterMetrics::RecordStartLocalSessionSuccessful(true);
-  MediaRouterMetrics::RecordStartLocalSessionSuccessful(false);
-  MediaRouterMetrics::RecordStartLocalSessionSuccessful(true);
+  TestRecordBooleanMetric(
+      base::BindRepeating(
+          &MediaRouterMetrics::RecordStartLocalSessionSuccessful),
+      MediaRouterMetrics::kHistogramStartLocalSessionSuccessful);
+}
 
-  tester.ExpectTotalCount(
-      MediaRouterMetrics::kHistogramStartLocalSessionSuccessful, 3);
-  EXPECT_THAT(tester.GetAllSamples(
-                  MediaRouterMetrics::kHistogramStartLocalSessionSuccessful),
-              ElementsAre(Bucket(false, 1), Bucket(true, 2)));
+TEST(MediaRouterMetricsTest, RecordSearchSinkOutcome) {
+  TestRecordBooleanMetric(
+      base::BindRepeating(&MediaRouterMetrics::RecordSearchSinkOutcome),
+      MediaRouterMetrics::kHistogramRecordSearchSinkOutcome);
 }
 
 }  // namespace media_router

chrome/browser/ui/webui/media_router/media_router_ui.cc

@@ -336,6 +336,7 @@ void MediaRouterUI::OnSearchSinkResponseReceived(
   handler_->ReturnSearchResult(found_sink_id);
 
   CreateRoute(found_sink_id, cast_mode);
+  MediaRouterMetrics::RecordSearchSinkOutcome(!found_sink_id.empty());
 }
 
 void MediaRouterUI::InitCommon(content::WebContents* initiator) {

tools/metrics/histograms/histograms.xml

@@ -43220,6 +43220,15 @@ uploading your change for review.
   </summary>
 </histogram>
 
+<histogram name="MediaRouter.Sink.SearchOutcome" enum="BooleanSuccess">
+  <owner>takumif@chromium.org</owner>
+  <summary>
+    The outcome of querying Media Route Providers for a sink by ID.
+    &quot;Success&quot; indicates that a sink was found. This is recorded when
+    the user attempts to cast to a sink with a manually entered ID.
+  </summary>
+</histogram>
+
 <histogram name="MediaRouter.Sink.SelectedType" enum="MediaSinkType">
   <owner>takumif@chromium.org</owner>
   <summary>