Add LICENSE and README.chromium files.

BUG=

Add these files so that the DEPS changes can pass the try bots which test for these files.

Review URL: https://webrtc-codereview.appspot.com/1116006

git-svn-id: http://webrtc.googlecode.com/svn/deps/third_party/openmax@3624 4adac7df-926f-26a2-2b94-8c16560cd09d