Standardize usage of virtual/override/final specifiers.

ui/views/controls/button/image_button.h

Index: ui/views/controls/button/image_button.h
diff --git a/ui/views/controls/button/image_button.h b/ui/views/controls/button/image_button.h
index dc861c4207d4b5ea391eba1efe5cb7c59498a2c4..bb3f526fea95093eb0d6e714fd29b9ceb6fbbc45 100644
--- a/ui/views/controls/button/image_button.h
+++ b/ui/views/controls/button/image_button.h
@@ -38,7 +38,7 @@ class VIEWS_EXPORT ImageButton : public CustomButton {
   };
 
   explicit ImageButton(ButtonListener* listener);
-  virtual ~ImageButton();
+  ~ImageButton() override;
 
   // Returns the image for a given |state|.
   virtual const gfx::ImageSkia& GetImage(ButtonState state) const;
@@ -69,14 +69,14 @@ class VIEWS_EXPORT ImageButton : public CustomButton {
   }
 
   // Overridden from View:
-  virtual gfx::Size GetPreferredSize() const override;
-  virtual const char* GetClassName() const override;
-  virtual void OnPaint(gfx::Canvas* canvas) override;
+  gfx::Size GetPreferredSize() const override;
+  const char* GetClassName() const override;
+  void OnPaint(gfx::Canvas* canvas) override;
 
  protected:
   // Overridden from View:
-  virtual void OnFocus() override;
-  virtual void OnBlur() override;
+  void OnFocus() override;
+  void OnBlur() override;
 
   // Returns the image to paint. This is invoked from paint and returns a value
   // from images.
@@ -127,7 +127,7 @@ class VIEWS_EXPORT ImageButton : public CustomButton {
 class VIEWS_EXPORT ToggleImageButton : public ImageButton {
  public:
   explicit ToggleImageButton(ButtonListener* listener);
-  virtual ~ToggleImageButton();
+  ~ToggleImageButton() override;
 
   // Change the toggled state.
   void SetToggled(bool toggled);
@@ -141,14 +141,13 @@ class VIEWS_EXPORT ToggleImageButton : public ImageButton {
   void SetToggledTooltipText(const base::string16& tooltip);
 
   // Overridden from ImageButton:
-  virtual const gfx::ImageSkia& GetImage(ButtonState state) const override;
-  virtual void SetImage(ButtonState state,
-                        const gfx::ImageSkia* image) override;
+  const gfx::ImageSkia& GetImage(ButtonState state) const override;
+  void SetImage(ButtonState state, const gfx::ImageSkia* image) override;
 
   // Overridden from View:
-  virtual bool GetTooltipText(const gfx::Point& p,
-                              base::string16* tooltip) const override;
-  virtual void GetAccessibleState(ui::AXViewState* state) override;
+  bool GetTooltipText(const gfx::Point& p,
+                      base::string16* tooltip) const override;
+  void GetAccessibleState(ui::AXViewState* state) override;
 
  private:
   // The parent class's images_ member is used for the current images,