Log time spent on different UI surfaces

- When swipe happens on worskpace, elapsed container ms is reset
- Fling DOWN is also logged so that we now know how much time was spent on
  all apps screen
- If screen off or power button trigger onPause, log this event.

Bug: 67745115
Change-Id: Ie3a0090c78195a4a028de9935131e9e034dcf48a
diff --git a/protos/launcher_log.proto b/protos/launcher_log.proto
index 0bbec18..de74fce 100644
--- a/protos/launcher_log.proto
+++ b/protos/launcher_log.proto
@@ -132,7 +132,9 @@
                   // not using the HOME_INTENT
     CANCEL = 3;   // Indicates that a confirmation screen was cancelled
     CONFIRM = 4;  // Indicates thata confirmation screen was accepted
+    STOP = 5;     // Indicates onStop() was called (screen time out, power off)
   }
+
   optional Type type = 1;
   optional Touch touch = 2;
   optional Direction dir = 3;