Implement AutomationNode.querySelector().

extensions/common/extension_messages.h

Index: extensions/common/extension_messages.h
diff --git a/extensions/common/extension_messages.h b/extensions/common/extension_messages.h
index d2aadea6b5859d8bf80f4f5d9e9eda185d87a129..54380316396705ea9c56bf843588b23ddcbe62f1 100644
--- a/extensions/common/extension_messages.h
+++ b/extensions/common/extension_messages.h
@@ -750,3 +750,18 @@ IPC_MESSAGE_CONTROL4(ExtensionHostMsg_CreateMimeHandlerViewGuest,
                      std::string /* embedder_url */,
                      std::string /* mime_type */,
                      int /* element_instance_id */)
+
+// Sent when a query selector request is made from the automation API.
+// acc_obj_id is the accessibility tree ID of the starting element.
+IPC_MESSAGE_ROUTED3(ExtensionMsg_AutomationQuerySelector,
+                    int /* request_id */,
+                    int /* acc_obj_id */,
+                    base::string16 /* selector */)
+
+// Result of a query selector request.
+// result_acc_obj_id is the accessibility tree ID of the result element; 0
+// indicates no result.
+IPC_MESSAGE_ROUTED3(ExtensionHostMsg_AutomationQuerySelector_Result,
+                    int /* request_id */,
+                    std::string /* error */,
+                    int /* result_acc_obj_id */)