Build fix. Make overriding methods virtual to satisfy clang.

ui/views/bubble/bubble_border_2.h

Index: ui/views/bubble/bubble_border_2.h
diff --git a/ui/views/bubble/bubble_border_2.h b/ui/views/bubble/bubble_border_2.h
index b0386ec7bd4bc5005cdb77deb3bf1db267e67992..d3a4f2588e95fbe60b56e119aaadaa9f4dcfae0b 100644
--- a/ui/views/bubble/bubble_border_2.h
+++ b/ui/views/bubble/bubble_border_2.h
@@ -47,7 +47,7 @@ class VIEWS_EXPORT BubbleBorder2 : public BubbleBorder {
   void SetShadow(gfx::ShadowValue shadow);
 
   // views::BubbleBorder overrides:
-  int GetBorderThickness() const OVERRIDE;
+  virtual int GetBorderThickness() const OVERRIDE;
 
  protected:
   void PaintBackground(gfx::Canvas* canvas,
@@ -61,8 +61,9 @@ class VIEWS_EXPORT BubbleBorder2 : public BubbleBorder {
   virtual void GetInsets(gfx::Insets* insets) const OVERRIDE;
   virtual gfx::Rect GetBounds(const gfx::Rect& position_relative_to,
                               const gfx::Size& contents_size) const OVERRIDE;
-  void GetInsetsForArrowLocation(gfx::Insets* insets,
-                                 ArrowLocation arrow_loc) const OVERRIDE;
+  virtual void GetInsetsForArrowLocation(
+      gfx::Insets* insets,
+      ArrowLocation arrow_loc) const OVERRIDE;
 
   // views::Border overrides:
   virtual void Paint(const View& view,