Reland r105404 with compile warning fixed.

Reland r105404 with compile warning fix.

[Sync] Refactor non-frontend DTC to handle new API properly. 

We now support disconnecting the syncableservice from the syncer via 
it's sync change processor. AutofillProfile has been modified to support 
this. As a result of the refactor and this disconnect functionality, we don't 
need to block sync shutdown on datatypes implemented the new API, even 
if they don't run on the UI thread. 

From here on, datatypes that are not on the UI thread should have their 
controller inherit from NewNonFrontendDataTypeController, and should 
have their syncable service take ownership of the sync change processor it 
receives. 

A remaining TODO is to apply these changes to UI thread based datatypes. 
This involves having them all take ownership of their sync change processors 
(this change has their datatype controllers take ownership instead) 
and creating a new parent datatype controller class that is API aware, 
allowing us to remove the SyncableServiceAdapater completely. See 
crbug.com/100114.

BUG=96889
TEST=unit_tests, integration tests
TBR=akalin@chromium.org

Original codereview at: http://codereview.chromium.org/8065016/

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=105431