media::FFmpegVideoDecoder: remove ctor param |task_runner| and use a ThreadChecker instead.
This CL removed the |task_runner| passed on construction to
FFmpegVideoDecoder since: "... is used in just one location
for PostTask()ing. The class itself is otherwise mostly single
threaded (except perhaps construction), and passing a
|task_runner| as ctor argument is confusingly indicating the
opposite. A |thread_checker_| basically tells that a(ll) methods
are run in a given thread, whichever this is."
(from discussion in http://crrev.com/1438233003, which has
sadly been reverted for unrelated issues, and is going to be
relanded as http://crrev.com/1447343004).
Removal of this |task_runner| is also necessary for using these
two classes from WebRtc, see the linekd bug.
BUG=554737
TEST=This is a tiny change, all unittest and content_browsertests should cover it.
Review URL: https://codereview.chromium.org/1456993004
Cr-Commit-Position: refs/heads/master@{#360628}
7 files changed
