cc: Fix race condition in TaskGraphRunner unit tests.

Access to |run_task_ids_| on worker thread need to be protected
by a lock.

BUG=343351
TBR=vmpstr

Review URL: https://codereview.chromium.org/168913002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251628 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 251628
Make sure wallpaper apis only change wallpaper of the user who calls it


wallpaper api may be invoked by inactive user at multi profile mode. These
api calls should not change the wallpaper of active user. Instead, it should
only update the wallpaper cache (so the user switching animation is smooth).
This CL fixes the problem.

BUG=342895

Review URL: https://codereview.chromium.org/149613006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251629 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 251629