Mac a11y: Don't coerce textfield title change events to value change

It's not clear why we're doing this, since we already set the text
of text fields as "value", so this just suppresses legitimate title
changed notifications.

Bug: None
Change-Id: I75a9e4fe68262cb45b37f817fd38d28a3de8093f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1764273
Commit-Queue: Leonard Grey <lgrey@chromium.org>
Reviewed-by: Aaron Leventhal <aleventhal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#696875}

ui/accessibility/platform/ax_platform_node_mac.mm

@@ -311,11 +311,6 @@ void PostAnnouncementNotification(NSString* announcement) {
 }
 
 void NotifyMacEvent(AXPlatformNodeCocoa* target, ax::mojom::Event event_type) {
-  NSString* announcement_text = [target announcementTextForEvent:event_type];
-  if (announcement_text) {
-    PostAnnouncementNotification(announcement_text);
-    return;
-  }
   NSString* notification =
       [AXPlatformNodeCocoa nativeNotificationFromAXEvent:event_type];
   if (notification)
@@ -1150,27 +1145,21 @@ gfx::NativeViewAccessible AXPlatformNodeMac::GetNativeViewAccessible() {
 
 void AXPlatformNodeMac::NotifyAccessibilityEvent(ax::mojom::Event event_type) {
   GetNativeViewAccessible();
-  // Add mappings between ax::mojom::Event and NSAccessibility notifications
-  // using the EventMap above. This switch contains exceptions to those
-  // mappings.
-  switch (event_type) {
-    case ax::mojom::Event::kTextChanged:
-      // If the view is a user-editable textfield, this should change the value.
-      if (GetData().role == ax::mojom::Role::kTextField) {
-        NotifyMacEvent(native_node_, ax::mojom::Event::kValueChanged);
-        return;
-      }
-      break;
-    case ax::mojom::Event::kSelection:
-      // On Mac, map menu item selection to a focus event.
-      if (ui::IsMenuItem(GetData().role)) {
-        NotifyMacEvent(native_node_, ax::mojom::Event::kFocus);
-        return;
-      }
-      break;
-    default:
-      break;
+  // Handle special cases.
+  NSString* announcement_text =
+      [native_node_ announcementTextForEvent:event_type];
+  if (announcement_text) {
+    PostAnnouncementNotification(announcement_text);
+    return;
+  }
+  if (event_type == ax::mojom::Event::kSelection &&
+      ui::IsMenuItem(GetData().role)) {
+    // On Mac, map menu item selection to a focus event.
+    NotifyMacEvent(native_node_, ax::mojom::Event::kFocus);
+    return;
   }
+  // Otherwise, use mappings between ax::mojom::Event and NSAccessibility
+  // notifications from the EventMap above.
   NotifyMacEvent(native_node_, event_type);
 }