Enforce marking "override" for functions overriding Blink in components/test_runner/.

components/test_runner/mock_screen_orientation_client.h

Index: components/test_runner/mock_screen_orientation_client.h
diff --git a/components/test_runner/mock_screen_orientation_client.h b/components/test_runner/mock_screen_orientation_client.h
index 2a2b442a5122a020776292beb84cb3cec8aca48e..ad868541ca17b2b4a1d6fd1f4c52beabf98d1cc2 100644
--- a/components/test_runner/mock_screen_orientation_client.h
+++ b/components/test_runner/mock_screen_orientation_client.h
@@ -23,7 +23,7 @@ class TEST_RUNNER_EXPORT MockScreenOrientationClient
     : public NON_EXPORTED_BASE(blink::WebScreenOrientationClient) {
  public:
   explicit MockScreenOrientationClient();
-  virtual ~MockScreenOrientationClient();
+  ~MockScreenOrientationClient() override;
 
   void ResetData();
   void UpdateDeviceOrientation(blink::WebLocalFrame* main_frame,
@@ -34,9 +34,9 @@ class TEST_RUNNER_EXPORT MockScreenOrientationClient
 
  private:
   // From blink::WebScreenOrientationClient.
-  virtual void lockOrientation(blink::WebScreenOrientationLockType orientation,
-                               blink::WebLockOrientationCallback* callback);
-  virtual void unlockOrientation();
+  void lockOrientation(blink::WebScreenOrientationLockType orientation,
+                       blink::WebLockOrientationCallback* callback) override;
+  void unlockOrientation() override;
 
   void UpdateLockSync(blink::WebScreenOrientationLockType,
                       blink::WebLockOrientationCallback*);