Fix for a crash in NativeViewAccessibilityWin

ui/views/accessibility/native_view_accessibility_win.cc

Index: ui/views/accessibility/native_view_accessibility_win.cc
diff --git a/ui/views/accessibility/native_view_accessibility_win.cc b/ui/views/accessibility/native_view_accessibility_win.cc
index bf7cc645e872b00d9968162c9f55d9b47ac57eb1..023e31188e3b86e52d0cf58b05195f8c031d2b2f 100644
--- a/ui/views/accessibility/native_view_accessibility_win.cc
+++ b/ui/views/accessibility/native_view_accessibility_win.cc
@@ -529,8 +529,12 @@ STDMETHODIMP NativeViewAccessibilityWin::get_accChild(VARIANT var_child,
   }
 
   *disp_child = child_view->GetNativeViewAccessible();
-  (*disp_child)->AddRef();
-  return S_OK;
+  if (*disp_child) {
+    (*disp_child)->AddRef();
+    return S_OK;
+  }
+
+  return E_FAIL;
 }
 
 STDMETHODIMP NativeViewAccessibilityWin::get_accChildCount(LONG* child_count) {