a11y/Mac: Add screenreader support for SubtleNotificationView announcements.

chrome/browser/ui/cocoa/omnibox/omnibox_view_mac.mm

 // Copyright (c) 2012 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/omnibox/omnibox_view_mac.h"
 
 #include <Carbon/Carbon.h>  // kVK_Return
 
 #include "base/mac/foundation_util.h"
+#import "base/mac/sdk_forward_declarations.h"
 #include "base/memory/ptr_util.h"
 #include "base/metrics/histogram.h"
 #include "base/strings/string_util.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/autocomplete/chrome_autocomplete_scheme_classifier.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/search/search.h"
 #include "chrome/browser/themes/theme_service.h"
 #import "chrome/browser/ui/cocoa/browser_window_controller.h"
@@ skipping 20 matching lines @@
 #include "ui/base/clipboard/clipboard_util_mac.h"
 #import "ui/base/cocoa/cocoa_base_utils.h"
 #import "ui/base/l10n/l10n_util_mac.h"
 #include "ui/base/material_design/material_design_controller.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/gfx/color_palette.h"
 #include "ui/gfx/font.h"
 #include "ui/gfx/font_list.h"
 #include "ui/gfx/geometry/rect.h"
 
-// TODO(ellyjones): Remove this when the deployment target is 10.9 or later.
-extern NSString* const NSAccessibilityPriorityKey;
-
 using content::WebContents;
 
 // Focus-handling between |field_| and model() is a bit subtle.
 // Other platforms detect change of focus, which is inconvenient
 // without subclassing NSTextField (even with a subclass, the use of a
 // field editor may complicate things).
 //
 // model() doesn't actually do anything when it gains focus, it just
 // initializes.  Visible activity happens only after the user edits.
 // NSTextField delegate receives messages around starting and ending
@@ skipping 1094 matching lines @@
                               display_text);
   NSDictionary* notification_info = @{
       NSAccessibilityAnnouncementKey : announcement,
       NSAccessibilityPriorityKey :     @(NSAccessibilityPriorityHigh)
   };
   NSAccessibilityPostNotificationWithUserInfo(
       [field_ window],
       NSAccessibilityAnnouncementRequestedNotification,
       notification_info);
 }