[sync] Close blank overlay on settings page when re-auth tab is opened

The sync setup overlay displays a blank (translucent) grey box by
default, and relies on sync setup to display the appropriate content in
the overlay. This resulted in bugs like crbug.com/266300 and
crbug.com/177217, where a blank overlay was sometimes left remaining
on the settings page.

This patch does the following:
- Updates the CloseUI method in SyncSetupHandler to also close
  outstanding sync overlays
- Audits instances where sync setup is closed while the settings page
  remains visible, and calls CloseUI() in those instances

BUG=297377, 273896
TEST=Repro steps in 297377 should not result in a blank overlay

Review URL: https://codereview.chromium.org/24487002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225432 0039d316-1c4b-4281-b951-d872f2087c98
[cc] Don't access pixels without a lock

Fix a bug where we don't lock a nine patch layer's pixels before
accessing them.

BUG=296830

Review URL: https://codereview.chromium.org/24490002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225433 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 225433
Add AudioDecoderSelector::Abort().

This new functions isn't used by AudioRendererImpl yet.
AudioRendererImpl::Stop() doesn't wait for AudioDecoderSelector to finish.
But it's still good to add this function for completeness and be future ready.

BUG=222054
TEST=Added unittests.

Review URL: https://codereview.chromium.org/24495002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225434 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 225434