Announce drag-and-drop operations will be deprecated in A11y.

Aria-dropeffect and aria-grabbed are deprecated in aria 1.1.
Those properties are expected to be replaced by
a new feature in a future version of WAI-ARIA.
After that we will re-implement them following new spec.

For now, we do not deprecate them immediately
for backward compatibility and just notify it
by comments as "TODO".

Bug: none
Change-Id: I1701d2048158c209b9a09608c0904abc3bfb75d7
Reviewed-on: https://chromium-review.googlesource.com/867799Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#531944}

third_party/WebKit/Source/modules/accessibility/AXLayoutObject.cpp

@@ -1363,6 +1363,10 @@ bool AXLayoutObject::AriaHasPopup() const {
          RoleValue() == kTextFieldWithComboBoxRole;
 }
 
+// TODO : Aria-dropeffect and aria-grabbed are deprecated in aria 1.1
+// Also those properties are expected to be replaced by a new feature in
+// a future version of WAI-ARIA. After that we will re-implement them
+// following new spec.
 bool AXLayoutObject::SupportsARIADragging() const {
   const AtomicString& grabbed = GetAttribute(aria_grabbedAttr);
   return EqualIgnoringASCIICase(grabbed, "true") ||