Set the accessibility ViewProp in OnCreate in addition to Show, because...

chrome/browser/renderer_host/render_widget_host_view_win.cc

Index: chrome/browser/renderer_host/render_widget_host_view_win.cc
===================================================================
--- chrome/browser/renderer_host/render_widget_host_view_win.cc	(revision 75393)
+++ chrome/browser/renderer_host/render_widget_host_view_win.cc	(working copy)
@@ -841,6 +841,12 @@
   props_.push_back(views::SetWindowSupportsRerouteMouseWheel(m_hWnd));
   props_.push_back(new ViewProp(m_hWnd, kRenderWidgetHostViewKey,
                                 static_cast<RenderWidgetHostView*>(this)));
+  // Save away our HWND in the parent window as a property so that the
+  // accessibility code can find it.
+  accessibility_prop_.reset(new ViewProp(GetParent(),
+                                         kViewsNativeHostPropForAccessibility,
+                                         m_hWnd));
+
   return 0;
 }