[Extensions] Isolate ExtensionFunction results_ and error_

extensions/browser/quota_service_unittest.cc

Index: extensions/browser/quota_service_unittest.cc
diff --git a/extensions/browser/quota_service_unittest.cc b/extensions/browser/quota_service_unittest.cc
index 646be96015f1bb4b81136dce1644baf7d35567e0..c5d957670ff495816b00e512afd02f53d8e0ae70 100644
--- a/extensions/browser/quota_service_unittest.cc
+++ b/extensions/browser/quota_service_unittest.cc
@@ -66,7 +66,6 @@ class MockFunction : public ExtensionFunction {
   explicit MockFunction(const char* name) { set_name(name); }
 
   void SetArgs(const base::ListValue* args) override {}
-  std::string GetError() const override { return std::string(); }
   void SetError(const std::string& error) override {}
   void Destruct() const override { delete this; }
   ResponseAction Run() override { return RespondLater(); }