SyncFS v2: Add re-initialization code for temporary service failure case

Also run SyncEngineInitializer task at high priority.

BUG=240165
TEST=manual

Review URL: https://codereview.chromium.org/110113003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239771 0039d316-1c4b-4281-b951-d872f2087c98
Remove browser_version support in gpu blacklist.

BUG=327201
TEST=gpu_unittests, bots compile
R=kbr@chromium.org

Review URL: https://codereview.chromium.org/111193002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239772 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 239771
SVN changes up to revision 239772