Add a Restore() method to ValueStore and make StorageAPI use it

chrome/browser/extensions/api/storage/settings_sync_unittest.cc

Index: chrome/browser/extensions/api/storage/settings_sync_unittest.cc
diff --git a/chrome/browser/extensions/api/storage/settings_sync_unittest.cc b/chrome/browser/extensions/api/storage/settings_sync_unittest.cc
index afd33baa503a9f2fe35967c1b3820eef649a19b5..2322248199d8ec7dcf87211e9c4f7a47f91927c4 100644
--- a/chrome/browser/extensions/api/storage/settings_sync_unittest.cc
+++ b/chrome/browser/extensions/api/storage/settings_sync_unittest.cc
@@ -176,6 +176,18 @@ class TestingValueStoreFactory : public SettingsStorageFactory {
     return new_storage;
   }
 
+  virtual base::FilePath GetDatabasePath(
+      const base::FilePath& base_path,
+      const std::string& extension_id) OVERRIDE {
+    return base_path.AppendASCII(extension_id);
+  }
+
+  // Testing value stores don't actually create a real database. Don't delete
+  // any files.
+  virtual void DeleteDatabaseIfExists(
+      const base::FilePath& base_path,
+      const std::string& extension_id) OVERRIDE {}
+
  private:
   // SettingsStorageFactory is refcounted.
   virtual ~TestingValueStoreFactory() {}