Add user event logging for clear all button
Bug: 72222505

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Verified

UserEvent: action:TAP
UserEvent:  Source child:CLEAR_ALL_BUTTON
UserEvent:  Elapsed container 8142 ms, session 11322 ms, action 0 ms
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Change-Id: I3ace51c30129728017c5eb198c52ab1bfd94c0ac
diff --git a/protos/launcher_log.proto b/protos/launcher_log.proto
index 4013429..7e15434 100644
--- a/protos/launcher_log.proto
+++ b/protos/launcher_log.proto
@@ -106,6 +106,7 @@
   BACK_BUTTON = 11; // Deprecated, use enum Command instead
   // GO_TO_PLAYSTORE
   QUICK_SCRUB_BUTTON = 12;
+  CLEAR_ALL_BUTTON = 13;
 }
 
 // Used to define the action component of the LauncherEvent.