Add initial GTK web accessibility framework (new with valgrind fix).

content/browser/accessibility/browser_accessibility_mac.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_ACCESSIBILITY_BROWSER_ACCESSIBILITY_MAC_H_
 #define CONTENT_BROWSER_ACCESSIBILITY_BROWSER_ACCESSIBILITY_MAC_H_
 #pragma once
 
 #include <map>
 #include <utility>
 #include <vector>
 
 #include "base/memory/scoped_nsobject.h"
 #include "content/browser/accessibility/browser_accessibility.h"
+#include "content/common/content_export.h"
 
 @class BrowserAccessibilityCocoa;
 
 class BrowserAccessibilityMac : public BrowserAccessibility {
  public:
   // Implementation of BrowserAccessibility.
   virtual void PreInitialize() OVERRIDE;
   virtual void NativeReleaseReference() OVERRIDE;
 
   // Overrides from BrowserAccessibility.
   virtual void DetachTree(std::vector<BrowserAccessibility*>* nodes) OVERRIDE;
+  CONTENT_EXPORT virtual BrowserAccessibilityMac*
+      ToBrowserAccessibilityMac() OVERRIDE;
 
   // The BrowserAccessibilityCocoa associated with us.
   BrowserAccessibilityCocoa* native_view() const {
     return browser_accessibility_cocoa_;
   }
 
  private:
   // This gives BrowserAccessibility::Create access to the class constructor.
   friend class BrowserAccessibility;
 
   BrowserAccessibilityMac();
 
   // Allows access to the BrowserAccessibilityCocoa which wraps this.
   // BrowserAccessibility.
   // We own this object until our manager calls ReleaseReference;
   // thereafter, the cocoa object owns us.
   BrowserAccessibilityCocoa* browser_accessibility_cocoa_;
   DISALLOW_COPY_AND_ASSIGN(BrowserAccessibilityMac);
 };
 
 #endif // CONTENT_BROWSER_ACCESSIBILITY_BROWSER_ACCESSIBILITY_MAC_H_