Support presentational iframes and make use of them in the uber frame.

chrome/common/extensions/api/automation.idl

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // The <code>chrome.automation</code> API allows developers to access the
 // automation (accessibility) tree for the browser. The tree resembles the DOM
 // tree, but only exposes the <em>semantic</em> structure of a page. It can be
 // used to programmatically interact with a page by examining names, roles, and
 // states, listening for events, and performing actions on nodes.
 [nocompile] namespace automation {
@@ skipping 80 matching lines @@
     figcaption,
     figure,
     footer,
     form,
     grid,
     group,
     growArea,
     heading,
     helpTag,
     iframe,
+    iframePresentational,

[aboxhall, 2014/12/03 23:46:17]

Should we do anything special with this in the automation API? Based on
browser_accessibility[_win].cc it looks like we probably should. Feel free to
add a TODO for me or David to do something.

[dmazzoni, 2014/12/17 18:30:27]

My initial thought is for the automation api to virtually ignore iframes
entirely and treat them as an implementation detail. It should be rare that an
automation tool or AT should actually care

     ignored,
     imageMapLink,
     imageMap,
     image,
     inlineTextBox,
     labelText,
     legend,
     link,
     listBoxOption,
     listBox,
@@ skipping 245 matching lines @@
     // tree with a placeholder root node; listen for the "loadComplete" event to
     // get a notification that the tree has fully loaded (the previous root node
     // reference will stop working at or before this point).
     [nocompile] static void getTree(optional long tabId, RootCallback callback);
 
     // Get the automation tree for the whole desktop which consists of all on
     // screen views. Note this API is currently only supported on Chrome OS.
     [nocompile] static void getDesktop(RootCallback callback);
   };
 };