Revert of Migrate accessibility from RenderView to RenderFrame.

content/browser/renderer_host/render_view_host_delegate.h

Index: content/browser/renderer_host/render_view_host_delegate.h
diff --git a/content/browser/renderer_host/render_view_host_delegate.h b/content/browser/renderer_host/render_view_host_delegate.h
index 4a441236ce4f1afa9a62e021ad655f7a2a18dba4..a9dea8bd7a33d7d5926e4b2b062dc72c071a711a 100644
--- a/content/browser/renderer_host/render_view_host_delegate.h
+++ b/content/browser/renderer_host/render_view_host_delegate.h
@@ -51,6 +51,7 @@
 class SiteInstance;
 class WebContents;
 class WebContentsImpl;
+struct AXEventNotificationDetails;
 struct FileChooserParams;
 struct GlobalRequestID;
 struct NativeWebKeyboardEvent;
@@ -283,6 +284,10 @@
   // created by the RenderViewHost.
   virtual FrameTree* GetFrameTree();
 
+  // Invoked when an accessibility event is received from the renderer.
+  virtual void AccessibilityEventReceived(
+      const std::vector<AXEventNotificationDetails>& details) {}
+
  protected:
   virtual ~RenderViewHostDelegate() {}
 };