a11y: Exclude children of nested keyboard accessible controls from a11y tree.

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"
@@ skipping 271 matching lines @@
 
 - (NSString*)getStringAttribute:(ui::AXStringAttribute)attribute {
   std::string attributeValue;
   if (node_->GetStringAttribute(attribute, &attributeValue))
     return base::SysUTF8ToNSString(attributeValue);
   return nil;
 }
 
 // NSAccessibility informal protocol implementation.
 
 - (BOOL)accessibilityIsIgnored {

[tapted, 2017/04/05 06:03:33]

Should this be updated to include ui::AX_ROLE_IGNORED ?

(any chance that's a possible shortcut to fixing http://crbug.com/610589 ?)

[Patti Lor, 2017/04/11 05:40:45]

I think this already happens - AX_ROLE_IGNORED is mapped to
NSAccessibilityUnknownRole (see BuildRoleMap() above), because there isn't any
NSAccessibility*Role equivalent, and we check for NS...UnknownRole here already.

The change that actually ignores the ignored elements on Mac is line 299 below,
where we check -accessibilityIsIgnored in the hit tests. We wouldn't need it if
we used NVABase::HitTestSync() in -accessibilityHitTest since that would exclude
ignored elements for us, but I think that might be out of scope for this CL (it
might be needed to make hit testing go inside WebViews; currently the
WebContents is just one giant green square when hovering over it with
Accessibility Inspector on Mac).

   return [[self AXRole] isEqualToString:NSAccessibilityUnknownRole] ||
          node_->GetData().HasStateFlag(ui::AX_STATE_INVISIBLE);
 }
 
 - (id)accessibilityHitTest:(NSPoint)point {
   for (AXPlatformNodeCocoa* child in [self AXChildren]) {
-    if (NSPointInRect(point, child.boundsInScreen))
+    if (![child accessibilityIsIgnored] &&
+        NSPointInRect(point, [child boundsInScreen])) {
       return [child accessibilityHitTest:point];
+    }
   }
   return NSAccessibilityUnignoredAncestor(self);
 }
 
 - (BOOL)accessibilityNotifiesWhenDestroyed {
   return YES;
 }
 
 - (id)accessibilityFocusedUIElement {
   return node_->GetDelegate()->GetFocus();
@@ skipping 388 matching lines @@
   }
   NotifyMacEvent(native_node_, event_type);
 }
 
 int AXPlatformNodeMac::GetIndexInParent() {
   // TODO(dmazzoni): implement this.  http://crbug.com/396137
   return -1;
 }
 
 }  // namespace ui