[MediaNotification] Add UMA to record user clicking media notifications

chrome/android/java/src/org/chromium/chrome/browser/media/remote/ExpandedControllerActivity.java

Index: chrome/android/java/src/org/chromium/chrome/browser/media/remote/ExpandedControllerActivity.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/media/remote/ExpandedControllerActivity.java b/chrome/android/java/src/org/chromium/chrome/browser/media/remote/ExpandedControllerActivity.java
index d78d483eef21d94d2b5f935c9e3184df807d13f7..5d2d79aae095794b188d062028825fe2eb84453e 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/media/remote/ExpandedControllerActivity.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/media/remote/ExpandedControllerActivity.java
@@ -26,6 +26,7 @@ import com.google.android.gms.cast.CastMediaControlIntent;
 
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.media.remote.RemoteVideoInfo.PlayerState;
+import org.chromium.chrome.browser.metrics.LaunchFromNotificationUMA;
 import org.chromium.third_party.android.media.MediaController;
 
 /**
@@ -134,6 +135,8 @@ public class ExpandedControllerActivity
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
 
+        LaunchFromNotificationUMA.recordSource(getIntent());
+
         mMediaRouteController =
                 RemoteMediaPlayerController.instance().getCurrentlyPlayingMediaRouteController();