a11y: Add a11y information to views::Tab and manually ignore its a11y children.

ui/views/controls/tabbed_pane/tabbed_pane.h

Index: ui/views/controls/tabbed_pane/tabbed_pane.h
diff --git a/ui/views/controls/tabbed_pane/tabbed_pane.h b/ui/views/controls/tabbed_pane/tabbed_pane.h
index 4ff3c6922bd1c88733c943f7e2fa833d70e1e662..0209fe9c35047eab7ed2d2915bddc4496cad3cd7 100644
--- a/ui/views/controls/tabbed_pane/tabbed_pane.h
+++ b/ui/views/controls/tabbed_pane/tabbed_pane.h
@@ -15,7 +15,38 @@ namespace views {
 class Label;
 class Tab;
 class TabbedPaneListener;
-class TabStrip;
+
+namespace test {
+class TabbedPaneAccessibilityMacTest;
+class TabbedPaneTest;
+}
+
+// The tab strip shown above the tab contents.
+class TabStrip : public View {

[tapted, 2017/01/12 16:33:55]

nit: move this down, after the declaration for `class Tab` (after, since the
definitions appear in the .cc after the Tab:: definitions).

[Patti Lor, 2017/01/13 05:48:38]

Done, also added forward declaration for its use in TabbedPane private members.

+ public:
+  // Internal class name.
+  static const char kViewClassName[];
+
+  TabStrip();
+  ~TabStrip() override;
+
+  // Called by TabStrip when the selected tab changes. This function is only
+  // called if |from_tab| is not null, i.e., there was a previously selected
+  // tab.
+  virtual void OnSelectedTabChanged(Tab* from_tab, Tab* to_tab);
+
+  // Overridden from View:
+  const char* GetClassName() const override;
+  void OnPaintBorder(gfx::Canvas* canvas) override;
+
+  Tab* GetSelectedTab() const;
+  Tab* GetTabAtDeltaFromSelected(int delta) const;
+  Tab* GetTabAtIndex(int index) const;
+  int GetSelectedTabIndex() const;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(TabStrip);
+};
 
 // TabbedPane is a view that shows tabs. When the user clicks on a tab, the
 // associated view is displayed.
@@ -61,11 +92,8 @@ class VIEWS_EXPORT TabbedPane : public View {
   friend class FocusTraversalTest;
   friend class Tab;
   friend class TabStrip;
-  FRIEND_TEST_ALL_PREFIXES(TabbedPaneTest, AddAndSelect);
-  FRIEND_TEST_ALL_PREFIXES(TabbedPaneTest, ArrowKeyBindings);
-
-  // Get the Tab (the tabstrip view, not its content) at the valid |index|.
-  Tab* GetTabAt(int index);

[tapted, 2017/01/12 16:33:55]

@sky: this was an orphaned declaration. Friended test harnesses currently
implement it as 

   Tab* GetTabAt(int index) {
     return static_cast<Tab*>(tabbed_pane_->tab_strip_->child_at(index));
   }

but that requires the the compiler to either see the TabStrip* declaration
[current approach], or at least to know it can upcast to a views::View*. 

Alternatives/Extensions:
 - a reinterpret_cast from TabStrip* to View* could work, but is kinda ugly
(e.g. multiple inheritance could break it)
 - Provide GetTabAt() in tabbed_pane.cc [would only be used for tests]
 - tmp = GetSelectedTabIndex(); SelectTabAt(index); tab = GetSelectedTab();
SelectTabAt(tmp); return tab; [would probably work, but has side effects.]
 - move TabStrip to an internal namespace or separate file

[sky, 2017/01/12 16:39:21]

I'm ok with exposing the declaration.

[Patti Lor, 2017/01/13 05:48:38]

Thanks Trent and sky, leaving as-is then :)

+  friend class test::TabbedPaneTest;
+  friend class test::TabbedPaneAccessibilityMacTest;
 
   // Get the Tab (the tabstrip view, not its content) at the selected index.
   Tab* GetSelectedTab();
@@ -121,6 +149,8 @@ class Tab : public View {
   void OnGestureEvent(ui::GestureEvent* event) override;
   gfx::Size GetPreferredSize() const override;
   const char* GetClassName() const override;
+  void GetAccessibleNodeData(ui::AXNodeData* node_data) override;
+  bool HandleAccessibleAction(const ui::AXActionData& action_data) override;
   void OnFocus() override;
   void OnBlur() override;
   bool OnKeyPressed(const ui::KeyEvent& event) override;