Create an AutofillBackend interface

components/autofill/browser/webdata/autofill_webdata_backend.h

Index: components/autofill/browser/webdata/autofill_webdata_backend.h
diff --git a/components/autofill/browser/webdata/autofill_webdata_backend.h b/components/autofill/browser/webdata/autofill_webdata_backend.h
index b1ab6d63b089552b6c7f2106f0384181589e0374..bd77576198acee77a0e177f76c4b019654149a50 100644
--- a/components/autofill/browser/webdata/autofill_webdata_backend.h
+++ b/components/autofill/browser/webdata/autofill_webdata_backend.h
@@ -6,8 +6,10 @@
 #define COMPONENTS_AUTOFILL_BROWSER_WEBDATA_AUTOFILL_WEBDATA_BACKEND_H_
 
 #include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "components/autofill/browser/webdata/autofill_webdata.h"
+#include "components/autofill/browser/webdata/autofill_webdata_service.h"
 #include "components/autofill/common/form_field_data.h"
 #include "components/webdata/common/web_data_results.h"
 #include "components/webdata/common/web_data_service_base.h"
@@ -20,6 +22,7 @@ class AutofillChange;
 class AutofillProfile;
 class AutofillWebDataServiceObserverOnDBThread;
 class CreditCard;
+class SyncableAutofillDelegate;
 
 // Backend implentation for the AutofillWebDataService. This class runs on the
 // DB thread, as it handles reads and writes to the WebDatabase, and functions
@@ -101,6 +104,13 @@ class AutofillWebDataBackend
   // Remove an observer.
   void RemoveObserver(AutofillWebDataServiceObserverOnDBThread* observer);
 
+  // Initializes |delegate_| if it has not already been initialized, and returns
+  // a ptr to it asynchonously via |callback|.
+  void GetDelegate(
+      const AutofillWebDataService::DelegateOnDBCallback& callback,
+      const base::Closure& on_changed_callback,

[Ilya Sherman, 2013/05/07 00:02:43]

nit: Docs for this param

+      WebDatabase* db);
+
  protected:
   virtual ~AutofillWebDataBackend();
 
@@ -120,6 +130,10 @@ class AutofillWebDataBackend
 
   ObserverList<AutofillWebDataServiceObserverOnDBThread> db_observer_list_;
 
+  // Delegate which allows clients to do autofill work directly on th DB thread.
+  // Owned by us.
+  scoped_ptr<SyncableAutofillDelegate> delegate_;
+
   DISALLOW_COPY_AND_ASSIGN(AutofillWebDataBackend);
 };