Merge fixes and changed for Android AppRTCDemo from internal repo.

- Rename AppRTCDemoActivity to CallActivity and move UI controls
to a fragment.
- Add option to enable/disable statistics.
- Move peer connection and video constraints from URL to peer
connection client.
- Variable renaming.

R=jiayl@webrtc.org, wzh@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/33299004

Cr-Commit-Position: refs/heads/master@{#8319}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8319 4adac7df-926f-26a2-2b94-8c16560cd09d
20 files changed