Revert 239771 "SyncFS v2: Add re-initialization code for tempora..."

Lightly suspected of causing failures on CrOS:

http://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%20Tests%20%28dbg%29%282%29/builds/9981

> 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

TBR=kinuko@chromium.org

Review URL: https://codereview.chromium.org/111893007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239923 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 239923