a11y/Mac: Add screenreader support for SubtleNotificationView announcements.

base/mac/sdk_forward_declarations.h

 // 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.
 
 // This file contains forward declarations for items in later SDKs than the
 // default one with which Chromium is built (currently 10.10).
 // If you call any function from this header, be sure to check at runtime for
 // respondsToSelector: before calling these functions (else your code will crash
 // on older OS X versions that chrome still supports).
 
@@ skipping 45 matching lines @@
 // Define NSStrings only available in newer versions of the OSX SDK to force
 // them to be statically linked.
 // ----------------------------------------------------------------------------
 
 extern "C" {
 #if !defined(MAC_OS_X_VERSION_10_9) || \
     MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_9
 BASE_EXPORT extern NSString* const NSWindowDidChangeOcclusionStateNotification;
 BASE_EXPORT extern NSString* const CBAdvertisementDataOverflowServiceUUIDsKey;
 BASE_EXPORT extern NSString* const CBAdvertisementDataIsConnectable;
+BASE_EXPORT extern NSString* const NSAccessibilityPriorityKey;
 #endif  // MAC_OS_X_VERSION_10_9
 
 #if !defined(MAC_OS_X_VERSION_10_10) || \
     MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_10
 BASE_EXPORT extern NSString* const NSUserActivityTypeBrowsingWeb;
 BASE_EXPORT extern NSString* const NSAppearanceNameVibrantDark;
 BASE_EXPORT extern NSString* const NSAppearanceNameVibrantLight;
 #endif  // MAC_OS_X_VERSION_10_10
 }  // extern "C"
 
@@ skipping 146 matching lines @@
 
 // ----------------------------------------------------------------------------
 // The symbol for kCWSSIDDidChangeNotification is available in the
 // CoreWLAN.framework for OSX versions 10.6 through 10.10. The symbol is not
 // declared in the OSX 10.9+ SDK, so when compiling against an OSX 10.9+ SDK,
 // declare the symbol.
 // ----------------------------------------------------------------------------
 BASE_EXPORT extern "C" NSString* const kCWSSIDDidChangeNotification;
 
 #endif  // BASE_MAC_SDK_FORWARD_DECLARATIONS_H_