Introduce AccessibilityFocusRing.

chrome/browser/chromeos/ui/focus_ring_layer.h

Index: chrome/browser/chromeos/ui/focus_ring_layer.h
diff --git a/chrome/browser/chromeos/ui/focus_ring_layer.h b/chrome/browser/chromeos/ui/focus_ring_layer.h
index 478b7cc2ec96a51e23d2589097cae60f336bb011..a6e8a60e3c1b11b5902058ece1c68c598f38b83b 100644
--- a/chrome/browser/chromeos/ui/focus_ring_layer.h
+++ b/chrome/browser/chromeos/ui/focus_ring_layer.h
@@ -39,6 +39,14 @@ class FocusRingLayer : public ui::LayerDelegate {
   // the given root window.
   void Set(aura::Window* root_window, const gfx::Rect& bounds);
 
+  ui::Layer* layer() { return layer_.get(); }
+
+ protected:
+  // Updates |root_window_| and creates |layer_| if it doesn't exist,
+  // or if the root window has changed. Moves the layer to the top if
+  // it wasn't there already.
+  void CreateOrUpdateLayer(aura::Window* root_window, const char* layer_name);
+
  private:
   // ui::LayerDelegate overrides:
   virtual void OnPaintLayer(gfx::Canvas* canvas) OVERRIDE;
@@ -53,13 +61,13 @@ class FocusRingLayer : public ui::LayerDelegate {
   // The current root window containing the focused object.
   aura::Window* root_window_;
 
+  // The current layer.
+  scoped_ptr<ui::Layer> layer_;
+
   // The bounding rectangle of the focused object, in |root_window_|
   // coordinates.
   gfx::Rect focus_ring_;
 
-  // The current layer.
-  scoped_ptr<ui::Layer> layer_;
-
   DISALLOW_COPY_AND_ASSIGN(FocusRingLayer);
 };