Add event log for view_enqueue_input_event.

Log out the input events to help debugging unresponsive UI issues.

Examples:
06-15 19:00:53.725  2272  2272 I view_enqueue_input_event: [Motion - Cancel,NavigationBar0]
06-16 02:28:35.318  3650  3650 I view_enqueue_input_event: [Key - Cancel,com.google.android.apps.nexuslauncher/com.google.android.apps.nexuslauncher.NexusLauncherActivity]

Bug: 154660150
Test: Manual test of swiping screen and watch event log.

Change-Id: I08c6be21ec01d9da2c67e2b59c15ba780de227be