GitLab

This makes it so playback doesn't stall if one seeks into an unbuffered
region then seeks back into a buffered region.

BUG=132935


Review URL: https://chromiumcodereview.appspot.com/10835044

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@150489 0039d316-1c4b-4281-b951-d872f2087c98