Create an AutofillBackend interface

components/autofill/browser/webdata/syncable_service_delegate.h

Index: components/autofill/browser/webdata/syncable_service_delegate.h
diff --git a/components/autofill/browser/webdata/syncable_service_delegate.h b/components/autofill/browser/webdata/syncable_service_delegate.h
new file mode 100644
index 0000000000000000000000000000000000000000..8bd49b07c3ddd4638a53400ce1b7bf548287bd55
--- /dev/null
+++ b/components/autofill/browser/webdata/syncable_service_delegate.h
@@ -0,0 +1,44 @@
+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef COMPONENTS_AUTOFILL_BROWSER_WEBDATA_SYNCABLE_SERVICE_DELEGATE_H_
+#define COMPONENTS_AUTOFILL_BROWSER_WEBDATA_SYNCABLE_SERVICE_DELEGATE_H_
+
+class WebDatabase;
+
+namespace autofill {
+
+class AutofillWebDataBackend;
+class AutofillWebDataServiceObserverOnDBThread;
+
+// Delegate class for doing Autofill work directly on the DB thread (used by
+// Sync, mostly), without fully exposing the AutofillWebDataBackend to clients.
+class SyncableServiceDelegate {

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

I'm still trying to wrap my mind around what this class is meant to be used for.
 Would it make sense to name this class "AutofillWebdataBackend", and modify the
existing class to be named AutofillWebdataBackendImpl and inherit from this one?

[Cait (Slow), 2013/05/07 19:22:07]

Done.

+ public:
+  virtual ~SyncableServiceDelegate() {}
+
+  virtual WebDatabase* GetDatabase() = 0;
+
+  // Add an observer to |autofill_backend_|.

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

nit: This class doesn't have an |autofill_backend_| variable.

[Cait (Slow), 2013/05/07 19:22:07]

Done.

+  virtual void AddObserver(
+      AutofillWebDataServiceObserverOnDBThread* observer) = 0;
+
+  // Remove an observer from |autofill_backend_|.

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

Ditto.

[Cait (Slow), 2013/05/07 19:22:07]

Done.

+  virtual void RemoveObserver(
+      AutofillWebDataServiceObserverOnDBThread* observer) = 0;
+
+  // Remove expired elements from |web_database_| and commit if needed.
+  virtual void RemoveExpiredFormElements() = 0;
+
+  // Notifies listeners on the UI thread that multiple changes have been made to
+  // to Autofill records of the database.
+  // NOTE: This method is intended to be called from the DB thread.  It
+  // it asynchronously notifies listeners on the UI thread.
+  // |web_data_service| may be NULL for testing purposes.
+  virtual void NotifyOfMultipleAutofillChanges() = 0;
+};
+
+} // autofill
+
+#endif //COMPONENTS_AUTOFILL_BROWSER_WEBDATA_SYNCABLE_SERVICE_DELEGATE_H_