Implement AutomationNode.querySelector().

chrome/common/extensions/api/automation.idl

Index: chrome/common/extensions/api/automation.idl
diff --git a/chrome/common/extensions/api/automation.idl b/chrome/common/extensions/api/automation.idl
index 015af4b583ad57322ae4c3d807a01cb13a3f60e5..9da10e0121c2b7066c00e612286a4b1aa88d265b 100644
--- a/chrome/common/extensions/api/automation.idl
+++ b/chrome/common/extensions/api/automation.idl
@@ -220,6 +220,9 @@
     long height;
   };
 
+  // Called when the result for a <code>query</code> is available.
+  callback QueryCallback = void(AutomationNode node);
+
   // An event in the Automation tree.
   [nocompile, noinline_doc] dictionary AutomationEvent {
     // The $(ref:automation.AutomationNode) to which the event was targeted.
@@ -289,6 +292,22 @@
     // Removes a listener for the given event type and event phase.
     static void removeEventListener(
         EventType eventType, AutomationListener listener, boolean capture);
+
+    // Gets the first node in this node's subtree which matches the given CSS
+    // selector and is within the same DOM context.
+    //
+    // If this node doesn't correspond directly with an HTML node in the DOM,
+    // querySelector will be run on this node's nearest HTML node ancestor. Note
+    // that this may result in the query returning a node which is not a
+    // descendant of this node.
+    //
+    // If the selector matches a node which doesn't directly correspond to an
+    // automation node (for example an element within an ARIA widget, where the
+    // ARIA widget forms one node of the automation tree, or an element which
+    // is hidden from accessibility via hiding it using CSS or using
+    // aria-hidden), this will return the nearest ancestor which does correspond
+    // to an automation node.
+    static void querySelector(DOMString selector, QueryCallback callback);
   };
 
   // Called when the <code>AutomationNode</code> for the page is available.