Add test for accessibility histograms.

content/browser/accessibility/browser_accessibility_state_impl.h

Index: content/browser/accessibility/browser_accessibility_state_impl.h
diff --git a/content/browser/accessibility/browser_accessibility_state_impl.h b/content/browser/accessibility/browser_accessibility_state_impl.h
index 40d99fd409f24be80fd7ee7bb5aca25ae2dc143e..46621eab631cb9214a1ef145dfd552358116c627 100644
--- a/content/browser/accessibility/browser_accessibility_state_impl.h
+++ b/content/browser/accessibility/browser_accessibility_state_impl.h
@@ -45,9 +45,7 @@ class CONTENT_EXPORT BrowserAccessibilityStateImpl
   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();
+  virtual void UpdateHistogramsForTesting() OVERRIDE;
 
   AccessibilityMode GetAccessibilityMode();
   void SetAccessibilityMode(AccessibilityMode mode);
@@ -56,6 +54,10 @@ class CONTENT_EXPORT BrowserAccessibilityStateImpl
   friend class base::RefCountedThreadSafe<BrowserAccessibilityStateImpl>;
   friend struct DefaultSingletonTraits<BrowserAccessibilityStateImpl>;
 
+  // Called a short while after startup to allow time for the accessibility
+  // state to be determined. Updates histograms with the current state.
+  void UpdateHistograms();
+
   // Leaky singleton, destructor generally won't be called.
   virtual ~BrowserAccessibilityStateImpl();