[MediaRouter] Record DIAL device counts in DialMediaSinkServiceImpl

chrome/browser/media/router/discovery/dial/dial_media_sink_service_impl.cc

Index: chrome/browser/media/router/discovery/dial/dial_media_sink_service_impl.cc
diff --git a/chrome/browser/media/router/discovery/dial/dial_media_sink_service_impl.cc b/chrome/browser/media/router/discovery/dial/dial_media_sink_service_impl.cc
index cf8b03d66b609d691a40aac38f5b070249f14741..de8a6632fd17f66cccfcc844eb66c50a8338c3bd 100644
--- a/chrome/browser/media/router/discovery/dial/dial_media_sink_service_impl.cc
+++ b/chrome/browser/media/router/discovery/dial/dial_media_sink_service_impl.cc
@@ -5,12 +5,18 @@
 #include "chrome/browser/media/router/discovery/dial/dial_media_sink_service_impl.h"
 
 #include "chrome/browser/media/router/discovery/dial/dial_device_data.h"
+#include "chrome/browser/media/router/media_router_metrics.h"
 #include "chrome/browser/profiles/profile.h"
 #include "content/public/browser/browser_thread.h"
 #include "net/url_request/url_request_context_getter.h"
 
 using content::BrowserThread;
 
+namespace {
+// How long to wait between device counts metrics are recorded. Set to 1 hour.
+const int kDeviceCountMetricThresholdMins = 60 * 60;

[imcheng, 2017/06/02 21:34:51]

I think this should be just 60?

[zhaobin, 2017/06/05 23:20:55]

Fixed in media_router_metrics.cc

+}
+
 namespace media_router {
 
 DialMediaSinkServiceImpl::DialMediaSinkServiceImpl(
@@ -129,4 +135,14 @@ void DialMediaSinkServiceImpl::OnDeviceDescriptionError(
   DVLOG(2) << "OnDescriptionFetchesError [message]: " << error_message;
 }
 
+void DialMediaSinkServiceImpl::RecordDeviceCounts() {
+  if (base::Time::Now() - device_count_metrics_record_time_ <

[imcheng, 2017/06/02 21:34:51]

Can the time check logic be part of MediaSinkServiceBase? That way, it can be
shared with other implementations.

[mark a. foltz, 2017/06/02 22:06:40]

I would rather bookkeeping for recording UMA live in MediaRouterMetrics, unless
there is some state that is tied to a specific instance of an object.  I think
DMSS is a singleton so maybe we can move this.

[zhaobin, 2017/06/05 23:20:55]

Done.

+      base::TimeDelta::FromMinutes(kDeviceCountMetricThresholdMins)) {
+    return;
+  }
+  MediaRouterMetrics::RecordDialDeviceCounts(current_sinks_.size(),
+                                             current_devices_.size());
+  device_count_metrics_record_time_ = base::Time::Now();
+}
+
 }  // namespace media_router