a11y/Mac: Add screenreader support for SubtleNotificationView announcements.

ui/accessibility/platform/ax_platform_node_mac.mm

 // Copyright 2014 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.
 
 #import "ui/accessibility/platform/ax_platform_node_mac.h"
 
 #import <Cocoa/Cocoa.h>
 #include <stddef.h>
 
 #include "base/macros.h"
+#import "base/mac/sdk_forward_declarations.h"
 #include "base/strings/sys_string_conversions.h"
 #include "ui/accessibility/ax_node_data.h"
 #include "ui/accessibility/ax_view_state.h"
 #include "ui/accessibility/platform/ax_platform_node_delegate.h"
 #import "ui/gfx/mac/coordinate_conversion.h"
 
 namespace {
 
 struct RoleMapEntry {
   ui::AXRole value;
@@ skipping 171 matching lines @@
   };
 
   RoleMap subrole_map;
   for (size_t i = 0; i < arraysize(subroles); ++i)
     subrole_map[subroles[i].value] = subroles[i].nativeValue;
   return subrole_map;
 }
 
 EventMap BuildEventMap() {
   const EventMapEntry events[] = {
+      {ui::AX_EVENT_CHILDREN_CHANGED, NSAccessibilityLayoutChangedNotification},
       {ui::AX_EVENT_TEXT_CHANGED, NSAccessibilityTitleChangedNotification},
-      {ui::AX_EVENT_VALUE_CHANGED, NSAccessibilityValueChangedNotification},
       {ui::AX_EVENT_TEXT_SELECTION_CHANGED,
        NSAccessibilitySelectedTextChangedNotification},
+      {ui::AX_EVENT_VALUE_CHANGED, NSAccessibilityValueChangedNotification},
       // TODO(patricialor): Add more events.
   };
 
   EventMap event_map;
   for (size_t i = 0; i < arraysize(events); ++i)
     event_map[events[i].value] = events[i].nativeValue;
   return event_map;
 }
 
 void NotifyMacEvent(NSView* target, ui::AXEvent event_type) {
@@ skipping 335 matching lines @@
     native_node_.reset([[AXPlatformNodeCocoa alloc] initWithNode:this]);
   return native_node_.get();
 }
 
 void AXPlatformNodeMac::NotifyAccessibilityEvent(ui::AXEvent event_type) {
   NSView* target = GetDelegate()->GetTargetForNativeAccessibilityEvent();
 
   // Add mappings between ui::AXEvent and NSAccessibility notifications using
   // the EventMap above. This switch contains exceptions to those mappings.
   switch (event_type) {
+    case ui::AX_EVENT_ALERT: {
+      NSString* announcement = base::SysUTF8ToNSString(
+          GetData().GetStringAttribute(ui::AX_ATTR_NAME));
+      NSDictionary* notification_info = @{
+        NSAccessibilityAnnouncementKey : announcement,
+        NSAccessibilityPriorityKey : @(NSAccessibilityPriorityHigh)
+      };
+      NSAccessibilityPostNotificationWithUserInfo(
+          [NSApp mainWindow], NSAccessibilityAnnouncementRequestedNotification,
+          notification_info);
+      return;
+    }
     case ui::AX_EVENT_TEXT_CHANGED:
       // If the view is a user-editable textfield, this should change the value.
       if (GetData().role == ui::AX_ROLE_TEXT_FIELD) {
         NotifyMacEvent(target, ui::AX_EVENT_VALUE_CHANGED);
         return;
       }
       break;
     default:
       break;
   }
   NotifyMacEvent(target, event_type);
 }
 
 int AXPlatformNodeMac::GetIndexInParent() {
   // TODO(dmazzoni): implement this.  http://crbug.com/396137
   return -1;
 }
 
 }  // namespace ui