WIP: enable unit tests on B2G.
Temporary patch: disable content process permission check for camera & PSM.
WIP: [experiment] HW accelerated video codec for WebRTC on B2G.
[WIP] Bug 911046 - WebRTC OmxCodec coding path support.
- use graphic buffer to reduce decoder CPU usage ('adb shell setprop webrtc.omx 3' to enable it)
- issues found:
  * frame drop
  * camera freeze
  * random crash
[WIP] Bug 911046 - Fix typo that causes build break when DEBUG enabled.