[Ozone] Removing Stub SFO implementation & CreateTestHelper from SFO

Given we now use the OzonePlatform to initialize SFO and we already have a test
implementation(the file backend), the Stub implementation isn't required. After
the removal the unittests will default to using the file backend.

This change also fixes the recent brakage of aura_unittests since the Stub SFO
returns 0 (kNullAcceleratedWidget) for a widget, which triggers a DCHECK
failure in WindowTreeHost::DestroyCompositor.

BUG=

Review URL: https://codereview.chromium.org/131493005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@245377 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 245377
Update DecoratedTextfield layout on icon changes.

Call Layout to update newly visible icon bounds.
Remove incorrect inset modifications for icons.

BUG=334132
TEST=rAc dialogs show icons as intended.
R=estade@chromium.org

Review URL: https://codereview.chromium.org/140653004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@245378 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 245378