Pause the sync thread while starting data types.

A few things to note:
- I ended the plubming (it's-a me, mario!) at the SyncBackendHost (the PSS does not know about pausing).  The SyncBackendHost now has RequestPause/RequestResume methods.  The notifications that are sent when pause and resume is complete are dispatched to the notification service by the SyncBackendHost.
- Calls to SHB::Request(Pause|Resume) go directly to the similar named methods on the SyncerThread.  This is unlike other methods on the SHB which are usually dispatched to the "core" thread before calling deeper into the onion.  I did this to avoid having to deal with callbacks to carry the result value of pause/resume (since the methods can fail and return false).  If this is a problem I can change the way it works.
- There is a little trickery regarding the integration unit tests since we typically use a specially initialized SBH for these tests, and the syncer thread does not really run for these tests.  Since the thread is not running, pause and resume won't work properly.  To get around this, the DataTypeManagerImpl in these tests is constructed with a mock SBH that will respond properly to pause and resume requests.

BUG=37154,37553

Review URL: http://codereview.chromium.org/1063002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@41883 0039d316-1c4b-4281-b951-d872f2087c98

0 files changed, 0 insertions, 0 deletions