Enumerate MJPEG as the prefered format if set.

Enumerate MJPEG as the prefered format if set.
This make sure that if it has been decided that MJPEG should be used in DirectShow
after enumerating the device capabilities, the input pin enumerates MJPEG as the onle and only format.

BUG=454869
Committed: https://crrev.com/9d2eae585146f128074c316dbf8d8a1d4da99f07
Cr-Commit-Position: refs/heads/master@{#314828}

[perkj_chrome, 2015-02-05 12:42:56]

perkj@chromium.org changed reviewers:
+ magjed@chromium.org

[perkj_chrome, 2015-02-05 12:42:57]

Can you please review?

[magjed_chromium, 2015-02-05 12:47:32]

lgtm % nit

https://codereview.chromium.org/900233002/diff/20001/media/video/capture/win/...
File media/video/capture/win/sink_input_pin_win.cc (right):

https://codereview.chromium.org/900233002/diff/20001/media/video/capture/win/...
media/video/capture/win/sink_input_pin_win.cc:52: if (index == 0) {
I would prefer:
if (index != 0)
  return false;

[perkj_chrome, 2015-02-05 13:08:42]

New patchsets have been uploaded after l-g-t-m from magjed@chromium.org

[perkj_chrome, 2015-02-05 16:22:29]

The CQ bit was checked by perkj@chromium.org

[commit-bot: I haz the power, 2015-02-05 16:22:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/900233002/40001

[commit-bot: I haz the power, 2015-02-05 17:19:26]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-02-05 17:20:30]

Patchset 3 (id:??) landed as
https://crrev.com/9d2eae585146f128074c316dbf8d8a1d4da99f07
Cr-Commit-Position: refs/heads/master@{#314828}