Allow focus to move into an editable combobox's listbox

In bug 593646 (https://codereview.chromium.org/2024053003/) a rule was
added, apparently similar to a rule in WebKit, that prevents
aria-activedescendant on an editable combobox field from moving focus
into its listbox. However, removing this condition fixes an issue where
the first item is not read. It also improves the verbalization,
providing the user with the positional info, e.g. "2 of 5".
Removing this line also does not seem to break the example attached to
bug 593646.

Bug: 1082865
Change-Id: I4250fb152f4b06f3c57b300ebe7ef5549c58d624
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2303789Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: Aaron Leventhal <aleventhal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#790502}

content/browser/accessibility/browser_accessibility_manager_mac.mm

@@ -140,11 +140,6 @@ BrowserAccessibility* BrowserAccessibilityManagerMac::GetFocus() const {
   if (!focus)
     return nullptr;
 
-  // For editable combo boxes, focus should stay on the combo box so the user
-  // will not be taken out of the combo box while typing.
-  if (focus->GetRole() == ax::mojom::Role::kTextFieldWithComboBox)
-    return focus;
-
   // Otherwise, follow the active descendant.
   return GetActiveDescendant(focus);
 }

content/test/data/accessibility/aria/aria-combobox-expected-mac.txt

 AXWebArea
 ++AXGroup
 ++++AXStaticText AXValue='State'
-++AXComboBox AXAutocompleteValue='list' AXFocused=1 AXTitle='State'
+++AXComboBox AXAutocompleteValue='list' AXTitle='State'
 ++AXList
 ++++AXStaticText AXValue='Alabama'
-++++AXStaticText AXValue='Alaska'
+++++AXStaticText AXFocused=1 AXValue='Alaska'
\ No newline at end of file

content/test/data/accessibility/event/aria-combo-box-collapse-expected-mac.txt

 AXExpandedChanged on AXComboBox
-AXSelectedChildrenChanged on AXComboBox
+AXFocusedUIElementChanged on AXComboBox
+AXSelectedChildrenChanged on AXComboBox
\ No newline at end of file

content/test/data/accessibility/event/aria-combo-box-delay-add-list-expected-mac.txt

-AXSelectedChildrenChanged on AXComboBox
+AXFocusedUIElementChanged on AXStaticText AXValue="Apple"
+AXSelectedChildrenChanged on AXComboBox
\ No newline at end of file

content/test/data/accessibility/event/aria-combo-box-delay-show-list-expected-mac.txt

+AXFocusedUIElementChanged on AXStaticText AXValue="Apple"
 AXSelectedChildrenChanged on AXComboBox
 AXSelectedChildrenChanged on AXList
\ No newline at end of file

content/test/data/accessibility/event/aria-combo-box-expand-expected-mac.txt

 AXExpandedChanged on AXComboBox
+AXFocusedUIElementChanged on AXStaticText AXValue="Apple"
 AXSelectedChildrenChanged on AXComboBox
-AXSelectedChildrenChanged on AXList
+AXSelectedChildrenChanged on AXList
\ No newline at end of file

content/test/data/accessibility/event/aria-combo-box-focus-expected-mac.txt

-AXFocusedUIElementChanged on AXComboBox
-AXSelectedTextChanged on AXComboBox
-AXSelectedTextChanged on AXWebArea
+AXFocusedUIElementChanged on AXStaticText AXValue="Apple not selected"
+AXSelectedTextChanged on AXStaticText AXValue="Apple not selected"
+AXSelectedTextChanged on AXWebArea
\ No newline at end of file

content/test/data/accessibility/event/aria-combo-box-next-expected-mac.txt

+AXFocusedUIElementChanged on AXStaticText AXValue="Orange"
 AXSelectedChildrenChanged on AXComboBox
 AXSelectedChildrenChanged on AXList
 === Start Continuation ===
+AXFocusedUIElementChanged on AXStaticText AXValue="Banana"
 AXSelectedChildrenChanged on AXComboBox
-AXSelectedChildrenChanged on AXList
+AXSelectedChildrenChanged on AXList
\ No newline at end of file