Fall back to software mode if Aura can't create a GL context

Wire up fallback from Compositor::CreateOutputSurface to
ContextFactory::CreateOutputSurface, so that we force using
the software compositor after failing to create a GL context
enough times.

BUG=319267

Review URL: https://codereview.chromium.org/93593002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238382 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 238382