Win Video Capture: Check returned AM_MEDIA_TYPE pointer before comparing it.

Win Video Capture: Check returned AM_MEDIA_TYPE pointer before comparing it.

See crash trace in the bug.

BUG=423664
Committed: https://crrev.com/bd35c4823694541a2a63bd194aeb45f2ab7bdd2e
Cr-Commit-Position: refs/heads/master@{#299734}

[mcasas, 2014-10-15 16:21:42]

mcasas@chromium.org changed reviewers:
+ perkj@chromium.org, tommi@chromium.org

[mcasas, 2014-10-15 16:21:43]

tommi@/perkj@ PTAL.

Plz read:
https://code.google.com/p/chromium/issues/detail?id=423664#c1

[mcasas, 2014-10-15 16:27:26]

Patchset #1 (id:1) has been deleted

[mcasas, 2014-10-15 16:31:36]

Patchset #1 (id:20001) has been deleted

[tommi (sloooow) - chröme, 2014-10-15 17:23:30]

The CQ bit was checked by tommi@chromium.org

[tommi (sloooow) - chröme, 2014-10-15 17:23:31]

lgtm

https://codereview.chromium.org/655293002/diff/40001/media/video/capture/win/...
File media/video/capture/win/video_capture_device_factory_win.cc (right):

https://codereview.chromium.org/655293002/diff/40001/media/video/capture/win/...
media/video/capture/win/video_capture_device_factory_win.cc:278: if (hr != S_OK
|| !media_type.get()) {
FYI - I checked the bug and just to confirm - this is exactly what's happening. 
The pointer isn't set by the implementation (which incorrectly returns S_OK), so
media_type wraps a NULL pointer to AM_MEDIA_TYPE and then we attempt to check
the |majortype| member, which is the first member variable of the struct (i.e.
offset 0 from the pointer), and we subsequently deref NULL.

[commit-bot: I haz the power, 2014-10-15 17:24:17]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/655293002/40001

[commit-bot: I haz the power, 2014-10-15 19:05:24]

Committed patchset #1 (id:40001)

[commit-bot: I haz the power, 2014-10-15 19:05:59]

Patchset 1 (id:??) landed as
https://crrev.com/bd35c4823694541a2a63bd194aeb45f2ab7bdd2e
Cr-Commit-Position: refs/heads/master@{#299734}