Add Chrome OS accessibility histograms.

content/browser/accessibility/browser_accessibility_state_impl.h

 // Copyright (c) 2012 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_STATE_IMPL_H_
 #define CONTENT_BROWSER_ACCESSIBILITY_BROWSER_ACCESSIBILITY_STATE_IMPL_H_
 
+#include <vector>
+
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/singleton.h"
 #include "content/common/view_message_enums.h"
 #include "content/public/browser/browser_accessibility_state.h"
 
 namespace content {
 
 // The BrowserAccessibilityState class is used to determine if Chrome should be
 // customized for users with assistive technology, such as screen readers. We
@@ skipping 16 matching lines @@
     : public base::RefCountedThreadSafe<BrowserAccessibilityStateImpl>,
       public BrowserAccessibilityState {
  public:
   BrowserAccessibilityStateImpl();
 
   static BrowserAccessibilityStateImpl* GetInstance();
 
   virtual void OnAccessibilityEnabledManually() OVERRIDE;
   virtual void OnScreenReaderDetected() OVERRIDE;
   virtual bool IsAccessibleBrowser() OVERRIDE;
+  virtual void AddHistogramCallback(base::Closure callback) OVERRIDE;
 
   // Called a short while after startup to allow time for the accessibility
   // state to be determined. Updates a histogram with the current state.
   void UpdateHistogram();
 
   AccessibilityMode GetAccessibilityMode();
   void SetAccessibilityMode(AccessibilityMode mode);
 
  private:
   friend class base::RefCountedThreadSafe<BrowserAccessibilityStateImpl>;
   friend struct DefaultSingletonTraits<BrowserAccessibilityStateImpl>;
 
   // Leaky singleton, destructor generally won't be called.
   virtual ~BrowserAccessibilityStateImpl();
 
   void UpdatePlatformSpecificHistograms();
 
   AccessibilityMode accessibility_mode_;
 
+  std::vector<base::Closure> histogram_callbacks_;
+
   DISALLOW_COPY_AND_ASSIGN(BrowserAccessibilityStateImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_ACCESSIBILITY_BROWSER_ACCESSIBILITY_STATE_IMPL_H_