Standardize usage of virtual/override/final specifiers.

ash/test/test_screenshot_delegate.h

Index: ash/test/test_screenshot_delegate.h
diff --git a/ash/test/test_screenshot_delegate.h b/ash/test/test_screenshot_delegate.h
index ad8ec989588f66923f87f0b49971a22e88e12906..9c25920c36b4afb60a24020b49194153ff996348 100644
--- a/ash/test/test_screenshot_delegate.h
+++ b/ash/test/test_screenshot_delegate.h
@@ -16,13 +16,13 @@ namespace test {
 class TestScreenshotDelegate : public ScreenshotDelegate {
  public:
   TestScreenshotDelegate();
-  virtual ~TestScreenshotDelegate();
+  ~TestScreenshotDelegate() override;
 
   // Overridden from ScreenshotDelegate:
-  virtual void HandleTakeScreenshotForAllRootWindows() override;
-  virtual void HandleTakePartialScreenshot(
-      aura::Window* window, const gfx::Rect& rect) override;
-  virtual bool CanTakeScreenshot() override;
+  void HandleTakeScreenshotForAllRootWindows() override;
+  void HandleTakePartialScreenshot(aura::Window* window,
+                                   const gfx::Rect& rect) override;
+  bool CanTakeScreenshot() override;
 
   int handle_take_screenshot_count() const {
     return handle_take_screenshot_count_;