Moved ownership of camera thread to user image screen

Moved ownership of camera thread to user image screen.
Patch of http://codereview.chromium.org/4106015/show

BUG=chromium-os:8440
TEST=Ensure that there is no crash after taking picture. Try several times, as this is timing related.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=64800

[whywhat, 2010-11-02 15:03:05]

PTAL

[whywhat, 2010-11-02 16:07:30]

Actually this doesn't eliminate the race since OnUninitializeSuccess can still
be executed on UI thread and will unreference camera object faster than
DoUninitialize on camera thread will finish and unreference camera object. I
think the right fix would be to separate the owner of the thread and the object
that's referenced by thread's tasks.

[whywhat, 2010-11-02 17:18:54]

I uploaded a new fix with camera thread separated from camera object. The thread
is owned by user image screen now, so it doesn't matter on which thread camera
object is destroyed.
Please, take a look.

[whywhat, 2010-11-02 17:42:57]

+Scott for yet another pair of eyes :)

[DaveMoore, 2010-11-02 17:45:22]

LGTM.

[sky, 2010-11-02 17:51:58]

I haven't seen this code before, and as its multi-threaded it'll take me a while
to review. As Dave just signed off on it I'm not going to review it. If you
really want me to review it though, I will.

  -Scott

http://codereview.chromium.org/4228002/diff/4001/5001
File chrome/browser/chromeos/login/camera.cc (right):

http://codereview.chromium.org/4228002/diff/4001/5001#newcode129
chrome/browser/chromeos/login/camera.cc:129: Lock Camera::image_lock_;
Style guide says no static objects, use a pointer instead.

[whywhat, 2010-11-02 19:10:58]

I'm okay with Dave's LGTM. Thanks for reviewing anyway, Scott!

http://codereview.chromium.org/4228002/diff/4001/5001
File chrome/browser/chromeos/login/camera.cc (right):

http://codereview.chromium.org/4228002/diff/4001/5001#newcode129
chrome/browser/chromeos/login/camera.cc:129: Lock Camera::image_lock_;
On 2010/11/02 17:51:58, sky wrote:
> Style guide says no static objects, use a pointer instead.

Done.