[Sync] Fix thread-ordering-dependent NULL dereference in NewNonFrontendDTC

chrome/browser/sync/glue/non_frontend_data_type_controller.h

Index: chrome/browser/sync/glue/non_frontend_data_type_controller.h
diff --git a/chrome/browser/sync/glue/non_frontend_data_type_controller.h b/chrome/browser/sync/glue/non_frontend_data_type_controller.h
index 55f56d95f06f878c73f4b9247c7951e9a8955a74..791701c73f39ccdd586292fdae4b3689627d1950 100644
--- a/chrome/browser/sync/glue/non_frontend_data_type_controller.h
+++ b/chrome/browser/sync/glue/non_frontend_data_type_controller.h
@@ -66,8 +66,8 @@ class NonFrontendDataTypeController : public DataTypeController {
   // associate models. The default implementation is a no-op.
   // Return value:
   //   True - if models are ready and association can proceed.
-  //   False - if models are not ready. KickOffAssociation should be called
-  //           when the models are ready. Refer to Start(_) implementation.
+  //   False - if models are not ready. StartAssociationAsync should be called
+  //           when the models are ready.
   // Note: this is performed on the frontend (UI) thread.
   virtual bool StartModels();
 
@@ -78,10 +78,6 @@ class NonFrontendDataTypeController : public DataTypeController {
       const tracked_objects::Location& from_here,
       const base::Closure& task) = 0;
 
-  // Build sync components and associate models.
-  // Note: this is performed on the datatype's thread.
-  virtual void StartAssociation();
-
   // Datatype specific creation of sync components.
   // Note: this is performed on the datatype's thread.
   virtual void CreateSyncComponents() = 0;
@@ -107,10 +103,6 @@ class NonFrontendDataTypeController : public DataTypeController {
   // Note: this is performed on the frontend (UI) thread.
   virtual void StopModels();
 
-  // Disassociate the models and destroy the sync components.
-  // Note: this is performed on the datatype's thread.
-  virtual void StopAssociation();
-
   // Implementation of OnUnrecoverableError that lives on UI thread.
   virtual void OnUnrecoverableErrorImpl(
       const tracked_objects::Location& from_here,
@@ -131,12 +123,7 @@ class NonFrontendDataTypeController : public DataTypeController {
   // Post the association task to the thread the datatype lives on.
   // Note: this is performed on the frontend (UI) thread.
   // Return value: True if task posted successfully, False otherwise.
-  bool StartAssociationAsync();
-
-  // Post the StopAssociation task to the thread the datatype lives on.
-  // Note: this is performed on the frontend (UI) thread.
-  // Return value: True if task posted successfully, False otherwise.
-  bool StopAssociationAsync();
+  virtual bool StartAssociationAsync();
 
   // Accessors and mutators used by derived classes.
   ProfileSyncComponentsFactory* profile_sync_factory() const;
@@ -151,6 +138,19 @@ class NonFrontendDataTypeController : public DataTypeController {
   virtual void set_change_processor(ChangeProcessor* change_processor);
 
  private:
+  // Build sync components and associate models.
+  // Note: this is performed on the datatype's thread.
+  void StartAssociation();
+
+  // Post the StopAssociation task to the thread the datatype lives on.
+  // Note: this is performed on the frontend (UI) thread.
+  // Return value: True if task posted successfully, False otherwise.
+  bool StopAssociationAsync();
+
+  // Disassociate the models and destroy the sync components.
+  // Note: this is performed on the datatype's thread.
+  void StopAssociation();
+
   ProfileSyncComponentsFactory* const profile_sync_factory_;
   Profile* const profile_;
   ProfileSyncService* const profile_sync_service_;