Update {virtual,override} to follow C++11 style in content.

content/browser/accessibility/browser_accessibility_manager_win.h

Index: content/browser/accessibility/browser_accessibility_manager_win.h
diff --git a/content/browser/accessibility/browser_accessibility_manager_win.h b/content/browser/accessibility/browser_accessibility_manager_win.h
index 24c0b77ee7bc4610dab7e62c4a130dcafb643f5d..c33f5923b57cd96c963da0d274aacd4406622ffc 100644
--- a/content/browser/accessibility/browser_accessibility_manager_win.h
+++ b/content/browser/accessibility/browser_accessibility_manager_win.h
@@ -23,7 +23,7 @@ class CONTENT_EXPORT BrowserAccessibilityManagerWin
       BrowserAccessibilityDelegate* delegate,
       BrowserAccessibilityFactory* factory = new BrowserAccessibilityFactory());
 
-  virtual ~BrowserAccessibilityManagerWin();
+  ~BrowserAccessibilityManagerWin() override;
 
   static ui::AXTreeUpdate GetEmptyDocument();
 
@@ -37,8 +37,8 @@ class CONTENT_EXPORT BrowserAccessibilityManagerWin
   void MaybeCallNotifyWinEvent(DWORD event, BrowserAccessibility* node);
 
   // AXTree methods
-  virtual void OnNodeWillBeDeleted(ui::AXNode* node) override;
-  virtual void OnNodeCreated(ui::AXNode* node) override;
+  void OnNodeWillBeDeleted(ui::AXNode* node) override;
+  void OnNodeCreated(ui::AXNode* node) override;
 
   // BrowserAccessibilityManager methods
   void OnWindowFocused() override;