a11y/Mac: Add screenreader support for SubtleNotificationView announcements.

chrome/browser/ui/views/subtle_notification_view.h

Index: chrome/browser/ui/views/subtle_notification_view.h
diff --git a/chrome/browser/ui/views/subtle_notification_view.h b/chrome/browser/ui/views/subtle_notification_view.h
index c04296a91029066f04322064425481390ebb8cc4..34409def0623a90e8202c9e65beab5e354e7f2d7 100644
--- a/chrome/browser/ui/views/subtle_notification_view.h
+++ b/chrome/browser/ui/views/subtle_notification_view.h
@@ -11,6 +11,7 @@
 #include "ui/views/view.h"
 
 namespace views {
+class AXViewState;
 class Link;
 class LinkListener;
 class Widget;
@@ -37,6 +38,9 @@ class SubtleNotificationView : public views::View {
                                           SubtleNotificationView* view,
                                           bool accept_events);
 
+  // views::View:
+  void GetAccessibleState(ui::AXViewState* state) override;
+
  private:
   class InstructionView;