[Chromecast] Allow media metrics events with no app running

chromecast/base/metrics/cast_metrics_helper.cc

Index: chromecast/base/metrics/cast_metrics_helper.cc
diff --git a/chromecast/base/metrics/cast_metrics_helper.cc b/chromecast/base/metrics/cast_metrics_helper.cc
index 30f2810048cacb501b5a8968cdee10763e0ea1bf..30e24537cc290330262ada5081885ea232c897f0 100644
--- a/chromecast/base/metrics/cast_metrics_helper.cc
+++ b/chromecast/base/metrics/cast_metrics_helper.cc
@@ -128,6 +128,8 @@ void CastMetricsHelper::UpdateSDKInfo(const std::string& sdk_version) {
 
 void CastMetricsHelper::LogMediaPlay() {
   MAKE_SURE_THREAD(LogMediaPlay);
+  if (app_id_.empty())

[slan, 2015/11/25 01:22:25]

Did you consider setting a testing value for app_id_? That way we can follow
this codepath all the way down in our tests.

+    return;
   RecordSimpleAction(EncodeAppInfoIntoMetricsName(
       "MediaPlay",
       app_id_,
@@ -137,6 +139,8 @@ void CastMetricsHelper::LogMediaPlay() {
 
 void CastMetricsHelper::LogMediaPause() {
   MAKE_SURE_THREAD(LogMediaPause);
+  if (app_id_.empty())
+    return;
   RecordSimpleAction(EncodeAppInfoIntoMetricsName(
       "MediaPause",
       app_id_,