Use MediaFormat's crop rectangle when available instead of width/height.

Per Android media team, width/height is not always reliable. See:
https://github.com/google/ExoPlayer/blob/a7b88cd6a9bac4de5ef47b23e0d7fb50c570b3a6/library/src/main/java/com/google/android/exoplayer/MediaCodecVideoTrackRenderer.java#L319

R=qinmin@chromium.org
BUG=internal b/18224769

Review URL: https://codereview.chromium.org/698273003

Cr-Commit-Position: refs/heads/master@{#302739}
1 file changed