Update the system update animation.

Switch to a Wear-like intro/loop system. We don't have an intro yet,
but hopefully this will let Wear delete more code when they move to N.
Unlike them, we don't hard-code the number of frames: we just look to
see what we have available. We do hard-code the fps though.

Also add a graphics test mode so you can see a demo of the UI components
without having to actually apply an OTA.

Also fix a bug where default locale is null rather than en-US: it's
more useful to show _some_ text if we don't have a locale (which should
only be during development anyway).

Bug: http://b/26548285
Change-Id: I63422e3fef3c41109f924d96fb5ded0b3ae7815d
diff --git a/device.h b/device.h
index f74b6b0..5017782 100644
--- a/device.h
+++ b/device.h
@@ -68,6 +68,7 @@
         SHUTDOWN = 8,
         VIEW_RECOVERY_LOGS = 9,
         MOUNT_SYSTEM = 10,
+        RUN_GRAPHICS_TEST = 11,
     };
 
     // Return the list of menu items (an array of strings,