Add non-blocking sync code to ProfileSyncService

chrome/browser/sync/glue/sync_backend_host.h

Index: chrome/browser/sync/glue/sync_backend_host.h
diff --git a/chrome/browser/sync/glue/sync_backend_host.h b/chrome/browser/sync/glue/sync_backend_host.h
index caea2d08e4b9bb3102982f33b3b3ff10c013d7b0..5b8afdc5dc32846ff2ea1e5bf7da7869b10919cb 100644
--- a/chrome/browser/sync/glue/sync_backend_host.h
+++ b/chrome/browser/sync/glue/sync_backend_host.h
@@ -16,6 +16,7 @@
 #include "sync/internal_api/public/base/model_type.h"
 #include "sync/internal_api/public/configure_reason.h"
 #include "sync/internal_api/public/sessions/sync_session_snapshot.h"
+#include "sync/internal_api/public/sync_core_proxy.h"
 #include "sync/internal_api/public/sync_manager.h"
 #include "sync/internal_api/public/sync_manager_factory.h"
 #include "sync/internal_api/public/util/report_unrecoverable_error_function.h"
@@ -158,6 +159,10 @@ class SyncBackendHost : public BackendDataTypeConfigurer {
   // initialization is complete with OnBackendInitialized().
   virtual syncer::UserShare* GetUserShare() const = 0;
 
+  // Called on |frontend_loop_| to obtain a handle to the SyncCore needed by
+  // the non-blocking sync types to communicate with the server.
+  virtual syncer::SyncCoreProxy GetSyncCoreProxy() = 0;
+
   // Called from any thread to obtain current status information in detailed or
   // summarized form.
   virtual Status GetDetailedStatus() = 0;