IAccessible::get_accChild should only return a descendant.

ui/accessibility/platform/ax_platform_node_win_unittest.cc

Index: ui/accessibility/platform/ax_platform_node_win_unittest.cc
diff --git a/ui/accessibility/platform/ax_platform_node_win_unittest.cc b/ui/accessibility/platform/ax_platform_node_win_unittest.cc
index 08be59b21f144666f5a29ea699bc7229e6436549..d5a4f81e50179722388b85fd8b414ec38cd7837a 100644
--- a/ui/accessibility/platform/ax_platform_node_win_unittest.cc
+++ b/ui/accessibility/platform/ax_platform_node_win_unittest.cc
@@ -315,7 +315,8 @@ TEST_F(AXPlatformNodeWinTest, TestIAccessibleChildAndParent) {
     // Asking for child id 3 should fail.
     ScopedComPtr<IDispatch> result;
     ScopedVariant child3(3);
-    ASSERT_EQ(E_FAIL, root_iaccessible->get_accChild(child3, result.Receive()));
+    ASSERT_EQ(E_INVALIDARG,
+              root_iaccessible->get_accChild(child3, result.Receive()));
   }
 
   // We should be able to ask for the button by its unique id too.
@@ -332,6 +333,20 @@ TEST_F(AXPlatformNodeWinTest, TestIAccessibleChildAndParent) {
     ASSERT_EQ(result.get(), button_iaccessible);
   }
 
+  // We shouldn't be able to ask for the root node by its unique ID
+  // from one of its children, though.
+  LONG root_unique_id;
+  ScopedComPtr<IAccessible2> root_iaccessible2 =
+      ToIAccessible2(root_iaccessible);
+  root_iaccessible2->get_uniqueID(&root_unique_id);
+  ASSERT_LT(root_unique_id, 0);
+  {
+    ScopedComPtr<IDispatch> result;
+    ScopedVariant root_id_variant(root_unique_id);
+    ASSERT_EQ(E_INVALIDARG, button_iaccessible->get_accChild(root_id_variant,
+                                                             result.Receive()));
+  }
+
   // Now check parents.
   {
     ScopedComPtr<IDispatch> result;