MacViews a11y: Allow accessibility clients to set the AXValue on some controls.

ui/accessibility/platform/test_ax_node_wrapper.cc

Index: ui/accessibility/platform/test_ax_node_wrapper.cc
diff --git a/ui/accessibility/platform/test_ax_node_wrapper.cc b/ui/accessibility/platform/test_ax_node_wrapper.cc
index 9e2898d49a5f88d989a6fc77f63dc9f0145e2275..78743605399c57139efaff70c86dd310773809ee 100644
--- a/ui/accessibility/platform/test_ax_node_wrapper.cc
+++ b/ui/accessibility/platform/test_ax_node_wrapper.cc
@@ -120,6 +120,10 @@ bool TestAXNodeWrapper::SetStringValue(const base::string16& new_value) {
   return false;
 }
 
+bool TestAXNodeWrapper::CanSetStringValue() {
+  return false;
+}
+
 TestAXNodeWrapper::TestAXNodeWrapper(AXTree* tree, AXNode* node)
     : tree_(tree),
       node_(node),