content: convert accessibility notifications to observer usage

content/browser/renderer_host/render_view_host_impl.h

Index: content/browser/renderer_host/render_view_host_impl.h
diff --git a/content/browser/renderer_host/render_view_host_impl.h b/content/browser/renderer_host/render_view_host_impl.h
index 7d57852228eed7aa35d9390d22bdea8f6a2efc11..36a098611a9ab56a2afdc9d2b911f121d963d009 100644
--- a/content/browser/renderer_host/render_view_host_impl.h
+++ b/content/browser/renderer_host/render_view_host_impl.h
@@ -208,6 +208,12 @@ class CONTENT_EXPORT RenderViewHostImpl
   virtual void UpdateWebkitPreferences(
       const webkit_glue::WebPreferences& prefs) OVERRIDE;
   virtual void NotifyTimezoneChange() OVERRIDE;
+  virtual void SetAccessibilityLayoutCompleteCallbackForTesting(
+      const base::Closure& callback) OVERRIDE;
+  virtual void SetAccessibilityLoadCompleteCallbackForTesting(
+      const base::Closure& callback) OVERRIDE;
+  virtual void SetAccessibilityOtherCallbackForTesting(
+      const base::Closure& callback) OVERRIDE;
 
 #if defined(OS_ANDROID)
   virtual void ActivateNearestFindResult(int request_id,
@@ -652,6 +658,11 @@ class CONTENT_EXPORT RenderViewHostImpl
   // callbacks.
   std::map<int, JavascriptResultCallback> javascript_callbacks_;
 
+  // Accessibility callbacks.
+  base::Closure accessibility_layout_callback_;
+  base::Closure accessibility_load_callback_;
+  base::Closure accessibility_other_callback_;
+
   // True if the render view can be shut down suddenly.
   bool sudden_termination_allowed_;