Logging tron metrics for ambient display gestures

Introducing new TRON metric (ACTION_AMBIENT_GESTURE)
and implementing logging for metric in DozeService.java

BUG=27907309

Change-Id: I324b6ef65e251f62b277beb1cb76af25159dbd90
diff --git a/proto/src/metrics_constants.proto b/proto/src/metrics_constants.proto
index 1dcb13c..2a506d82 100644
--- a/proto/src/metrics_constants.proto
+++ b/proto/src/metrics_constants.proto
@@ -2219,6 +2219,12 @@
     // Notification group expansion state toggled by the expand gesture.
     ACTION_NOTIFICATION_GROUP_GESTURE_EXPANDER = 410;
 
+    // User performs gesture that activates the ambient display
+    // 1: Gesture performed is Nudge
+    // 2: Gesture performed is Pickup
+    // 4: Gesture performed is Double Tap
+    ACTION_AMBIENT_GESTURE = 411;
+
     // ---- End N Constants, all N constants go above this line ----
 
     // ------- Begin N App Disambig Shade -----