Increment a MetricsLogger counter on back press. am: 580135c1b8 am: 51ac3a911c

am: a774e10aec

Change-Id: Ia3f485d5eb05c9700d8ae612dea069b97de7bf11

services/core/java/com/android/server/policy/PhoneWindowManager.java

@@ -1083,6 +1083,7 @@ public class PhoneWindowManager implements WindowManagerPolicy {
     }
 
     private void interceptBackKeyDown() {
+        MetricsLogger.count(mContext, "key_back_down", 1);
         // Reset back key state for long press
         mBackKeyHandled = false;