Prevent VoiceOver from announcing omnibox and status bubble overlay windows.

chrome/browser/ui/cocoa/status_bubble_mac.mm

 // Copyright (c) 2011 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.
 
 #include "chrome/browser/ui/cocoa/status_bubble_mac.h"
 
 #include <limits>
 
 #include "base/compiler_specific.h"
 #include "base/mac/mac_util.h"
@@ skipping 359 matching lines @@
   // We do not need to worry about the bubble outliving |parent_| because our
   // teardown sequence in BWC guarantees that |parent_| outlives the status
   // bubble and that the StatusBubble is torn down completely prior to the
   // window going away.
   scoped_nsobject<BubbleView> view(
       [[BubbleView alloc] initWithFrame:NSZeroRect themeProvider:parent_]);
   [window_ setContentView:view];
 
   [window_ setAlphaValue:0.0];
 
+  // TODO(dtseng): Ignore until we provide NSAccessibility support.
+  [window_ accessibilitySetOverrideValue:NSAccessibilityUnknownRole
+      forAttribute:NSAccessibilityRoleAttribute];
+
   // Set a delegate for the fade-in and fade-out transitions to be notified
   // when fades are complete.  The ownership model is for window_ to own
   // animation_dictionary, which owns animation, which owns
   // animation_delegate.
   CAAnimation* animation = [[window_ animationForKey:kFadeAnimationKey] copy];
   [animation autorelease];
   StatusBubbleAnimationDelegate* animation_delegate =
       [[StatusBubbleAnimationDelegate alloc] initWithStatusBubble:this];
   [animation_delegate autorelease];
   [animation setDelegate:animation_delegate];
@@ skipping 334 matching lines @@
     }
 
     // Round the top corners when the bubble is below the parent window.
     if (NSMinY(window_frame) < NSMinY(parent_frame)) {
       corner_flags |= kRoundedTopLeftCorner | kRoundedTopRightCorner;
     }
   }
 
   return corner_flags;
 }