Re-work the thread restrictions on the DOM distiller database

components/dom_distiller/core/dom_distiller_store_unittest.cc

Index: components/dom_distiller/core/dom_distiller_store_unittest.cc
diff --git a/components/dom_distiller/core/dom_distiller_store_unittest.cc b/components/dom_distiller/core/dom_distiller_store_unittest.cc
index 9e4cf35f55023c8c69ab7a0d4e9fe29ff7f2f9b5..db777e93725474f8c727eba9ffd05a5e7928740f 100644
--- a/components/dom_distiller/core/dom_distiller_store_unittest.cc
+++ b/components/dom_distiller/core/dom_distiller_store_unittest.cc
@@ -55,8 +55,6 @@ class FakeDB : public DomDistillerDatabaseInterface {
  public:
   explicit FakeDB(EntryMap* db) : db_(db) {}
 
-  virtual void Destroy() OVERRIDE {}
-
   virtual void Init(
       const base::FilePath& database_dir,
       DomDistillerDatabaseInterface::InitCallback callback) OVERRIDE {