Add test for accessibility histograms.

content/public/browser/browser_accessibility_state.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_PUBLIC_BROWSER_BROWSER_ACCESSIBILITY_STATE_H_
 #define CONTENT_PUBLIC_BROWSER_BROWSER_ACCESSIBILITY_STATE_H_
 
 #include "base/callback_forward.h"
 #include "content/common/content_export.h"
 
@@ skipping 16 matching lines @@
   virtual void OnScreenReaderDetected() = 0;
 
   // Returns true if the browser should be customized for accessibility.
   virtual bool IsAccessibleBrowser() = 0;
 
   // Add a callback method that will be called once, a small while after the
   // browser starts up, when accessibility state histograms are updated.
   // Use this to register a method to update additional accessibility
   // histograms.
   virtual void AddHistogramCallback(base::Closure callback) = 0;
+
+  virtual void UpdateHistogramsForTesting() = 0;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_BROWSER_ACCESSIBILITY_STATE_H_