Fix a problem that MSP will stop decoding data if there is no video present

If SetVideoSurface() gets called when there is no video config data, MSP will stop decoding more data because the ProcessPendingEvents() will early return. The behavior is wrong, If there is no video present, we should not early return.


BUG=321338

Review URL: https://codereview.chromium.org/68323007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237250 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237250