Add audio only watch time metrics.

media/blink/watch_time_reporter_unittest.cc

Index: media/blink/watch_time_reporter_unittest.cc
diff --git a/media/blink/watch_time_reporter_unittest.cc b/media/blink/watch_time_reporter_unittest.cc
index 6ab2957f726c1ff9960e7912af0817e091cc323a..0fc8ef24452c8e33e338a638568c59e62b2be4c3 100644
--- a/media/blink/watch_time_reporter_unittest.cc
+++ b/media/blink/watch_time_reporter_unittest.cc
@@ -246,9 +246,9 @@ TEST_F(WatchTimeReporterTest, WatchTimeReporter) {
   wtr_->OnPlaying();
   EXPECT_FALSE(IsMonitoring());
 
-  Initialize(true, false, true, true, kSizeJustRight);
+  Initialize(true, false, true, true, gfx::Size());
   wtr_->OnPlaying();
-  EXPECT_FALSE(IsMonitoring());
+  EXPECT_TRUE(IsMonitoring());
 
   constexpr gfx::Size kSizeTooSmall = gfx::Size(100, 100);
   Initialize(true, true, true, true, kSizeTooSmall);
@@ -266,6 +266,18 @@ TEST_F(WatchTimeReporterTest, WatchTimeReporter) {
   Initialize(true, true, true, false, kSizeJustRight);
   wtr_->OnPlaying();
   EXPECT_TRUE(IsMonitoring());
+
+  Initialize(true, false, true, true, gfx::Size());
+  wtr_->OnPlaying();
+  EXPECT_TRUE(IsMonitoring());
+
+  Initialize(true, false, false, false, gfx::Size());
+  wtr_->OnPlaying();
+  EXPECT_TRUE(IsMonitoring());
+
+  Initialize(true, false, true, false, gfx::Size());
+  wtr_->OnPlaying();
+  EXPECT_TRUE(IsMonitoring());
 }
 
 // Tests that basic reporting for the all category works.
@@ -290,6 +302,7 @@ TEST_F(WatchTimeReporterTest, WatchTimeReporterBasic) {
   EXPECT_WATCH_TIME(MediaLog::kWatchTimeAudioVideoMse, kWatchTimeLate);
   CycleReportingTimer();
 }
+
 // Tests that starting from a non-zero base works.
 TEST_F(WatchTimeReporterTest, WatchTimeReporterNonZeroStart) {
   constexpr base::TimeDelta kWatchTime1 = base::TimeDelta::FromSeconds(5);