Reland: Make 'click' the default action of unfocusable ARIA buttons

Trusty comes with a version of ATK that does not support the checkable
attribute, so we must specifically deny this in the test. A followup
change will make this global in order to avoid having to add it to many
tests.

Original commit message:
> Users of ATs on AuraLinux use the default action to know whether or not
> to activate nodes via the keyboard or a simulated mouse event. When a
> node with a button role cannot receive keyboard focus, have the default
> action be click. This heuristic helps ensure that when there is an ARIA
> button that cannot be activated via the keyboard, users know to simulate
> a mouse click.

Bug: 1025264
Change-Id: Ib8e66b369e30c771ce8533de24050f99e32ab579
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1953709Reviewed-by: Joanmarie Diggs <jdiggs@igalia.com>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: Martin Robinson <mrobinson@igalia.com>
Cr-Commit-Position: refs/heads/master@{#722496}

content/browser/accessibility/accessibility_tree_formatter_auralinux.cc

@@ -55,6 +55,7 @@ class AccessibilityTreeFormatterAuraLinux
       AtspiAccessible* node);
 
   void AddTextProperties(AtkText* atk_text, base::DictionaryValue* dict);
+  void AddActionProperties(AtkObject* atk_object, base::DictionaryValue* dict);
   void AddValueProperties(AtkObject* atk_object, base::DictionaryValue* dict);
   void AddTableProperties(AtkObject* atk_object, base::DictionaryValue* dict);
   void AddTableCellProperties(const ui::AXPlatformNodeAuraLinux* node,
@@ -242,6 +243,23 @@ void AccessibilityTreeFormatterAuraLinux::AddTextProperties(
   dict->Set("text", std::move(text_values));
 }
 
+void AccessibilityTreeFormatterAuraLinux::AddActionProperties(
+    AtkObject* atk_object,
+    base::DictionaryValue* dict) {
+  if (!ATK_IS_ACTION(atk_object))
+    return;
+
+  AtkAction* action = ATK_ACTION(atk_object);
+  int action_count = atk_action_get_n_actions(action);
+  if (!action_count)
+    return;
+
+  auto actions = std::make_unique<base::ListValue>();
+  for (int i = 0; i < action_count; i++)
+    actions->AppendString(atk_action_get_name(action, i));
+  dict->Set("actions", std::move(actions));
+}
+
 void AccessibilityTreeFormatterAuraLinux::AddValueProperties(
     AtkObject* atk_object,
     base::DictionaryValue* dict) {
@@ -448,6 +466,7 @@ void AccessibilityTreeFormatterAuraLinux::AddProperties(
 
   if (ATK_IS_TEXT(atk_object))
     AddTextProperties(ATK_TEXT(atk_object), dict);
+  AddActionProperties(atk_object, dict);
   AddValueProperties(atk_object, dict);
   AddTableProperties(atk_object, dict);
   AddTableCellProperties(ax_platform_node, atk_object, dict);
@@ -583,6 +602,23 @@ base::string16 AccessibilityTreeFormatterAuraLinux::ProcessTreeForOutput(
     }
   }
 
+  const base::ListValue* action_names_list;
+  std::vector<std::string> action_names;
+  if (node.GetList("actions", &action_names_list)) {
+    for (auto it = action_names_list->begin(); it != action_names_list->end();
+         ++it) {
+      std::string action_name;
+      if (it->GetAsString(&action_name))
+        action_names.push_back(action_name);
+    }
+    std::string actions_str = base::JoinString(action_names, ", ");
+    if (actions_str.size()) {
+      WriteAttribute(false,
+                     base::StringPrintf("actions=(%s)", actions_str.c_str()),
+                     &line);
+    }
+  }
+
   const base::ListValue* relations_value;
   if (node.GetList("relations", &relations_value)) {
     for (auto it = relations_value->begin(); it != relations_value->end();

content/test/data/accessibility/html/action-verbs-expected-auralinux.txt

+[document web] name='Action verbs'
+++[section]
+++++[static] name='Generic div'
+++[heading] name='Heading'
+++++[static] name='Heading'
+++[push button] name='Button' actions=(press)
+++[link] name='Link' actions=(jump)
+++++[static] name='Link' actions=(click-ancestor)
+++[entry] selectable-text actions=(activate)
+++[entry] selectable-text actions=(activate)
+++[entry] selectable-text actions=(activate)
+++[entry] selectable-text actions=(activate)
+++[check box] actions=(check) checkable:true
+++[check box] checked actions=(uncheck) checkable:true
+++[radio button] actions=(check) checkable:true
+++[toggle button] name='ARIA Switch' actions=(check) checkable:true
+++[panel]
+++++[toggle button] name='Summary' actions=(press)
+++++++[static] name='Summary'
+++[combo box] actions=(open)
+++++[menu]
+++++++[menu item] name='Pop-up button' selectable selected actions=(select)
+++[section] actions=(click)
+++++[static] name='Div with click handler' actions=(click-ancestor)
+++[panel] actions=(click)
+++++[paragraph] actions=(click-ancestor)
+++++++[static] name='Paragraph with click handler on parent' actions=(click-ancestor)
+++[menu]
+++++[menu item] name='Menu item 1' actions=(select)
+++++[check menu item] name='Menu item 2' checked actions=(uncheck) checkable:true
+++++[radio menu item] name='Menu item 3' actions=(check) checkable:true
+++[push button] name='ARIA Button' actions=(click)
+++[push button] name='ARIA button with tab index' actions=(press)
+++[push button] name='ARIA button with negative tab index' actions=(press)
+++[section]
+++++[push button] name='ARIA button that is an active descendant' actions=(press)

content/test/data/accessibility/html/action-verbs-expected-blink.txt

@@ -41,3 +41,16 @@ rootWebArea name='Action verbs'
 ++++++menuItem name='Menu item 1' defaultActionVerb=select
 ++++++menuItemCheckBox name='Menu item 2' defaultActionVerb=uncheck checkedState=true
 ++++++menuItemRadio name='Menu item 3' defaultActionVerb=check checkedState=false
+++++button name='ARIA Button' defaultActionVerb=click
+++++++staticText name='ARIA Button'
+++++++++inlineTextBox name='ARIA Button'
+++++button name='ARIA button with tab index' defaultActionVerb=press
+++++++staticText name='ARIA button with tab index'
+++++++++inlineTextBox name='ARIA button with tab index'
+++++button name='ARIA button with negative tab index' defaultActionVerb=press
+++++++staticText name='ARIA button with negative tab index'
+++++++++inlineTextBox name='ARIA button with negative tab index'
+++++genericContainer activedescendantId=button
+++++++button name='ARIA button that is an active descendant' defaultActionVerb=press
+++++++++staticText name='ARIA button that is an active descendant'
+++++++++++inlineTextBox name='ARIA button that is an active descendant'

content/test/data/accessibility/html/action-verbs-expected-uia-win.txt

@@ -29,3 +29,8 @@ document Name='Action verbs'
 ++++menuitem Name='Menu item 1'
 ++++menuitemcheckbox Name='Menu item 2' Toggle.ToggleState='On'
 ++++menuitemradio Name='Menu item 3' SelectionItem.IsSelected=false
+++button Name='ARIA Button'
+++button Name='ARIA button with tab index'
+++button Name='ARIA button with negative tab index'
+++group
+++++button Name='ARIA button that is an active descendant'

content/test/data/accessibility/html/action-verbs-expected-win.txt

@@ -29,3 +29,8 @@ ROLE_SYSTEM_DOCUMENT name='Action verbs' READONLY FOCUSABLE
 ++++ROLE_SYSTEM_MENUITEM name='Menu item 1' default_action='select' action_name='select'
 ++++IA2_ROLE_CHECK_MENU_ITEM name='Menu item 2' CHECKED IA2_STATE_CHECKABLE checkable:true default_action='uncheck' action_name='uncheck'
 ++++IA2_ROLE_RADIO_MENU_ITEM name='Menu item 3' IA2_STATE_CHECKABLE checkable:true default_action='check' action_name='check'
+++ROLE_SYSTEM_PUSHBUTTON name='ARIA Button' default_action='click' action_name='click'
+++ROLE_SYSTEM_PUSHBUTTON name='ARIA button with tab index' FOCUSABLE default_action='press' action_name='press'
+++ROLE_SYSTEM_PUSHBUTTON name='ARIA button with negative tab index' FOCUSABLE default_action='press' action_name='press'
+++IA2_ROLE_SECTION
+++++ROLE_SYSTEM_PUSHBUTTON name='ARIA button that is an active descendant' FOCUSABLE default_action='press' action_name='press'

content/test/data/accessibility/html/action-verbs.html

@@ -4,6 +4,8 @@
 @WIN-ALLOW:action_name*
 @WIN-ALLOW:default_action*
 @WIN-ALLOW:haspopup*
+@AURALINUX-ALLOW:actions*
+@AURALINUX-DENY:checkable
 -->
 <!doctype html>
 <html>
@@ -34,5 +36,11 @@
     <div role="menuitemcheckbox" aria-checked="true">Menu item 2</div>
     <div role="menuitemradio">Menu item 3</div>
   </div>
+  <div role="button">ARIA Button</div>
+  <div role="button" tabindex="1">ARIA button with tab index</div>
+  <div role="button" tabindex="-1">ARIA button with negative tab index</div>
+  <div aria-activedescendant="active-descendant-button">
+    <div role="button" id="active-descendant-button">ARIA button that is an active descendant</div>
+  </div>
 </body>
 </html>

third_party/blink/renderer/modules/accessibility/ax_object.cc

@@ -1866,6 +1866,17 @@ ax::mojom::DefaultActionVerb AXObject::Action() const {
                : ax::mojom::DefaultActionVerb::kUncheck;
   }
 
+  // If this object cannot receive focus and has a button role, use click as
+  // the default action. On the AuraLinux platform, the press action is a
+  // signal to users that they can trigger the action using the keyboard, while
+  // a click action means the user should trigger the action via a simulated
+  // click. If this object cannot receive focus, it's impossible to trigger it
+  // with a key press.
+  if (RoleValue() == ax::mojom::Role::kButton &&
+      !CanReceiveAccessibilityFocus()) {
+    return ax::mojom::DefaultActionVerb::kClick;
+  }
+
   switch (RoleValue()) {
     case ax::mojom::Role::kButton:
     case ax::mojom::Role::kDisclosureTriangle: