[MediaRouter] Record DIAL device counts in DialMediaSinkServiceImpl

chrome/browser/media/router/media_router_metrics.cc

Index: chrome/browser/media/router/media_router_metrics.cc
diff --git a/chrome/browser/media/router/media_router_metrics.cc b/chrome/browser/media/router/media_router_metrics.cc
index 3da4c634908d4ac17a1f8b82f1630b71f3d38a79..a64b98a813f488d074580d490e4188ca4ef9b2eb 100644
--- a/chrome/browser/media/router/media_router_metrics.cc
+++ b/chrome/browser/media/router/media_router_metrics.cc
@@ -6,10 +6,23 @@
 
 #include "base/macros.h"
 #include "base/metrics/histogram_macros.h"
+#include "base/time/default_clock.h"
+
+namespace {
+// How long to wait between device counts metrics are recorded. Set to 1 hour.
+const int kDeviceCountMetricThresholdMins = 60;
+}  // namespace
 
 namespace media_router {
 
+MediaRouterMetrics::MediaRouterMetrics() : clock_(new base::DefaultClock()) {}
+MediaRouterMetrics::~MediaRouterMetrics() = default;
+
 // static
+const char MediaRouterMetrics::kHistogramDialAvailableDeviceCount[] =
+    "MediaRouter.Dial.AvailableDevicesCount";
+const char MediaRouterMetrics::kHistogramDialKnownDeviceCount[] =
+    "MediaRouter.Dial.KnownDevicesCount";
 const char MediaRouterMetrics::kHistogramIconClickLocation[] =
     "MediaRouter.Icon.Click.Location";
 const char MediaRouterMetrics::kHistogramUiDialogPaint[] =
@@ -63,4 +76,20 @@ void MediaRouterMetrics::RecordRouteCreationOutcome(
       static_cast<int>(MediaRouterRouteCreationOutcome::TOTAL_COUNT));
 }
 
+void MediaRouterMetrics::RecordDialDeviceCounts(size_t available_device_count,
+                                                size_t known_device_count) {
+  if (clock_->Now() - device_count_metrics_record_time_ <
+      base::TimeDelta::FromMinutes(kDeviceCountMetricThresholdMins)) {
+    return;
+  }
+  UMA_HISTOGRAM_COUNTS_100(kHistogramDialAvailableDeviceCount,
+                           available_device_count);
+  UMA_HISTOGRAM_COUNTS_100(kHistogramDialKnownDeviceCount, known_device_count);
+  device_count_metrics_record_time_ = clock_->Now();
+}
+
+void MediaRouterMetrics::SetClockForTest(std::unique_ptr<base::Clock> clock) {
+  clock_ = std::move(clock);
+}
+
 }  // namespace media_router