sync: hook up ServerConnectionManager <> SyncerThread2 and tie up more loose ends

chrome/browser/sync/engine/syncapi.h

Index: chrome/browser/sync/engine/syncapi.h
diff --git a/chrome/browser/sync/engine/syncapi.h b/chrome/browser/sync/engine/syncapi.h
index 0d0d6910f4056c73d21e0d845ec0d1aac48671db..3f2cd00d41c5bfcaae57bcc5ca78559cb4aeadc9 100644
--- a/chrome/browser/sync/engine/syncapi.h
+++ b/chrome/browser/sync/engine/syncapi.h
@@ -43,6 +43,7 @@
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/callback.h"
 #include "base/gtest_prod_util.h"
 #include "base/scoped_ptr.h"
 #include "build/build_config.h"
@@ -828,6 +829,8 @@ class SyncManager {
     virtual ~Observer();
   };
 
+  typedef Callback0::Type ModeChangeCallback;
+
   // Create an uninitialized SyncManager.  Callers must Init() before using.
   SyncManager();
   virtual ~SyncManager();
@@ -925,6 +928,12 @@ class SyncManager {
   // TODO(tim): Deprecated.
   bool RequestResume();
 
+  // Puts the SyncerThread into a mode where no normal nudge or poll traffic
+  // will occur, but calls to RequestConfig will be supported.  If |callback|
+  // is provided, it will be invoked (from the internal SyncerThread) when
+  // the thread has changed to configuration mode.
+  void StartConfigurationMode(ModeChangeCallback* callback);
+
   // For the new SyncerThread impl, this switches the mode of operation to
   // CONFIGURATION_MODE and schedules a config task to fetch updates for
   // |types|. It is an error to call this with legacy SyncerThread in use.