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

content/browser/accessibility/browser_accessibility_win.cc

Index: content/browser/accessibility/browser_accessibility_win.cc
diff --git a/content/browser/accessibility/browser_accessibility_win.cc b/content/browser/accessibility/browser_accessibility_win.cc
index c8ee3ab8c123738028d9dd7922b86a0a3a8ded6b..ff3c0123151a8fc2757bcd29e43cb88b253cda29 100644
--- a/content/browser/accessibility/browser_accessibility_win.cc
+++ b/content/browser/accessibility/browser_accessibility_win.cc
@@ -3086,6 +3086,14 @@ void BrowserAccessibilityWin::OnDataChanged() {
     relation->AddTarget(title_elem_id);
     relations_.push_back(relation);
   }
+
+  // If this is a web area for a presentational iframe, give it a role of
+  // something other than DOCUMENT so that the fact that it's a separate doc
+  // is not exposed to AT.
+  if (IsWebAreaForPresentationalIframe()) {
+    ia_role_ = ROLE_SYSTEM_GROUPING;
+    ia2_role_ = ROLE_SYSTEM_GROUPING;
+  }
 }
 
 void BrowserAccessibilityWin::OnUpdateFinished() {
@@ -3555,10 +3563,12 @@ void BrowserAccessibilityWin::InitRoleAndState() {
       ia2_role_ = IA2_ROLE_HEADING;
       break;
     case ui::AX_ROLE_IFRAME:
-      ia_role_ = ROLE_SYSTEM_DOCUMENT;
       ia2_role_ = IA2_ROLE_INTERNAL_FRAME;
       ia_state_ = STATE_SYSTEM_READONLY;
       break;
+    case ui::AX_ROLE_IFRAME_PRESENTATIONAL:
+      ia_role_ = ROLE_SYSTEM_GROUPING;
+      break;
     case ui::AX_ROLE_IMAGE:
       ia_role_ = ROLE_SYSTEM_GRAPHIC;
       ia_state_ |= STATE_SYSTEM_READONLY;