[Sync] Add support for enabling session sync remotely.

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 21fe22a11a7b4172f0fba9ac4a9862ebe5e3f62d..6d874cac6bf097b0701b77bfa748d8f89a52b018 100644
--- a/chrome/browser/sync/glue/sync_backend_host.h
+++ b/chrome/browser/sync/glue/sync_backend_host.h
@@ -34,6 +34,7 @@
 
 class CancelableTask;
 class Profile;
+class ProfileSyncFactory;
 
 namespace net {
 class URLRequestContextGetter;
@@ -46,6 +47,7 @@ struct SyncSessionSnapshot;
 }
 
 class ChangeProcessor;
+class DataTypeController;
 class JsEventHandler;
 
 // SyncFrontend is the interface used by SyncBackendHost to communicate with
@@ -101,6 +103,16 @@ class SyncFrontend {
   virtual void OnMigrationNeededForTypes(
       const syncable::ModelTypeSet& types) = 0;
 
+  // Get the list of types that can be enabled.
+  virtual void GetRegisteredDataTypes(syncable::ModelTypeSet* types) const = 0;
+
+  // Get the list of types that are enabled.
+  virtual void GetPreferredDataTypes(syncable::ModelTypeSet* types) const = 0;
+
+  // Register a DataTypeController.
+  virtual void RegisterDataTypeController(
+      browser_sync::DataTypeController* data_type_controller) = 0;
+
  protected:
   // Don't delete through SyncFrontend interface.
   virtual ~SyncFrontend() {
@@ -134,6 +146,7 @@ class SyncBackendHost : public browser_sync::ModelSafeWorkerRegistrar {
   // bootstrap authentication using |lsid|, if it isn't empty.
   // Optionally delete the Sync Data folder (if it's corrupt).
   void Initialize(SyncFrontend* frontend,
+                  ProfileSyncFactory* factory,
                   const WeakHandle<JsEventHandler>& event_handler,
                   const GURL& service_url,
                   const syncable::ModelTypeSet& initial_types,
@@ -598,6 +611,9 @@ class SyncBackendHost : public browser_sync::ModelSafeWorkerRegistrar {
   // The frontend which we serve (and are owned by).
   SyncFrontend* frontend_;
 
+  // The factory for creating DataTypeControllers.
+  ProfileSyncFactory* profile_sync_factory_;
+
   // The change processors that handle the different data types.
   std::map<syncable::ModelType, ChangeProcessor*> processors_;