Adding support for retrying gclient sync.
Adding support for retrying gclient sync.

Moved sync code to a separate method.
Removed unclear usage of force_sync, build_enabled and build_only
booleaen flags.

BUG=None
TEST=Tested on local master with Mac and Linux slaves.

Review URL: https://webrtc-codereview.appspot.com/421001

git-svn-id: 917f5d3ca488f358c4d40eaec14422cf392ccec9@1795 4adac7df-926f-26a2-2b94-8c16560cd09d

mwgoldsmith/ilbc,mwgoldsmith/ilbc,TimothyGu/libilbc,mwgoldsmith/libilbc,ShiftMediaProject/libilbc,mwgoldsmith/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,mwgoldsmith/ilbc,TimothyGu/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,mwgoldsmith/libilbc,mwgoldsmith/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,mwgoldsmith/ilbc,ShiftMediaProject/libilbc