Remove opaque check in preparing dirty region

Since preserve swap is enabled, we need to clear the color buffer
when the scissor rect is prepared for a new process. This prevents
garbage being present from the previous process in the color buffer.

CRs-Fixed: 465346
Change-Id: I98f2009748244751c4b56af8afbdfeb645c13230
Merge remote-tracking branch 'upstream/jb-mr1' into test
Improve auto-brightness handling

- Add a setting to control the auto-brightness algorithm responsitivity
- Make the algorithm react much faster when the ambient brightness
  increases quickly, e.g. when receiving a call in bright sunlight.

Change-Id: Ic608901c476609dde69cae982228c09567140a83
Merge remote-tracking branch 'upstream/jb-mr1' into test