Some optimizations.

- Don't try to create a thumbnail bitmap on the client side.  This
  wastes 64k, and isn't needed since we are doing screenshots.
- Optimize View to put all of the callback pointers out of line.
  Added a couple new APIs so these don't need to be protected/public.
- Lazily create ViewGroup's cache paint.
- Change FrameworkPerf app to not use HW accel drawing, to give better
  comparison with GB.

Change-Id: Iec56d02459820d74a4cc9c7ec9c1856563c82c7b