Introduce AccessibilityFocusRing.

chrome/browser/chromeos/ui/accessibility_focus_ring_layer.h

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_CHROMEOS_UI_ACCESSIBILITY_FOCUS_RING_LAYER_H_
+#define CHROME_BROWSER_CHROMEOS_UI_ACCESSIBILITY_FOCUS_RING_LAYER_H_
+
+#include "chrome/browser/chromeos/ui/accessibility_focus_ring.h"
+#include "chrome/browser/chromeos/ui/focus_ring_layer.h"
+
+namespace aura {
+class Window;

[xiyuan, 2014/09/11 03:33:11]

nit: not used

[dmazzoni, 2014/09/11 21:44:39]

Done.

+}
+
+namespace ui {
+class Layer;
+}
+
+namespace chromeos {
+
+// A subclass of FocusRingLayer intended for use by ChromeVox; it supports
+// nonrectangular focus rings in order to highlight groups of elements or
+// a range of text on a page.
+class AccessibilityFocusRingLayer : public FocusRingLayer {
+ public:
+  explicit AccessibilityFocusRingLayer(FocusRingLayerDelegate* delegate);
+  virtual ~AccessibilityFocusRingLayer();
+
+  // Create the layer and update its bounds and position in the hierarchy.
+  void Set(const AccessibilityFocusRing& ring);
+
+ private:
+  // ui::LayerDelegate overrides:
+  virtual void OnPaintLayer(gfx::Canvas* canvas) OVERRIDE;
+
+  // The current layer.
+  scoped_ptr<ui::Layer> layer_;
+
+  // The outline of the current focus ring.
+  AccessibilityFocusRing ring_;
+
+  DISALLOW_COPY_AND_ASSIGN(AccessibilityFocusRingLayer);
+};
+
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_UI_ACCESSIBILITY_FOCUS_RING_LAYER_H_