Make Windows accessibility event firing aware of guest / child frames.

content/browser/accessibility/browser_accessibility_cocoa.mm

Index: content/browser/accessibility/browser_accessibility_cocoa.mm
diff --git a/content/browser/accessibility/browser_accessibility_cocoa.mm b/content/browser/accessibility/browser_accessibility_cocoa.mm
index 1b720658e242816b88432d9b22c9c6afb2ac7cf8..198f119c154c8aa738839f0d6dd6c5bc97419e50 100644
--- a/content/browser/accessibility/browser_accessibility_cocoa.mm
+++ b/content/browser/accessibility/browser_accessibility_cocoa.mm
@@ -25,6 +25,7 @@ extern "C" void NSAccessibilityUnregisterUniqueIdForUIElement(id element);
 
 using ui::AXNodeData;
 using content::BrowserAccessibility;
+using content::BrowserAccessibilityDelegate;
 using content::BrowserAccessibilityManager;
 using content::BrowserAccessibilityManagerMac;
 using content::ContentClient;
@@ -534,9 +535,16 @@ NSDictionary* attributeToMethodNameMap = nil;
   if (!browserAccessibility_)
     return NSZeroPoint;
 
-  gfx::Rect bounds(origin.x, origin.y, size.width, size.height);
-  gfx::Point point = [self delegate]->AccessibilityOriginInScreen(bounds);
-  return NSMakePoint(point.x(), point.y());
+  // Get the delegate for the topmost BrowserAccessibilityManager, because
+  // that's the only one that can convert points to their origin in the screen.
+  BrowserAccessibilityDelegate* delegate = GetDelegateFromRootManager();
+  if (delegate) {
+    gfx::Rect bounds(origin.x, origin.y, size.width, size.height);
+    gfx::Point point = delegate->AccessibilityOriginInScreen(bounds);
+    return NSMakePoint(point.x(), point.y());
+  } else {
+    return NSZeroPoint;
+  }
 }
 
 // Returns a string indicating the NSAccessibility role of this object.
@@ -1558,4 +1566,3 @@ NSDictionary* attributeToMethodNameMap = nil;
 }
 
 @end
-