GitLab

- This CL makes media_unittests linked.
- The audio_track_output_stub_android.cc is in place of
  audio_track_output_android.cc because the Java environment is not
  avaliable yet.
- Also changed to dependence on '../third_party/ffmpeg/ffmpeg.gyp'
  only if os is not Android in media.gyp.

BUG=
TEST=


Review URL: http://codereview.chromium.org/8718014

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@112739 0039d316-1c4b-4281-b951-d872f2087c98