Implement Chrome OS accessibility features to highlight focus, caret & cursor.

chrome/browser/chromeos/ui/accessibility_cursor_ring_layer.h

+// Copyright 2016 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_CURSOR_RING_LAYER_H_
+#define CHROME_BROWSER_CHROMEOS_UI_ACCESSIBILITY_CURSOR_RING_LAYER_H_
+
+#include "chrome/browser/chromeos/ui/accessibility_focus_ring.h"
+#include "chrome/browser/chromeos/ui/focus_ring_layer.h"
+
+namespace chromeos {
+
+// A subclass of FocusRingLayer that highlights the mouse cursor while it's
+// moving, to make it easier to find visually.
+class AccessibilityCursorRingLayer : public FocusRingLayer {
+ public:
+  explicit AccessibilityCursorRingLayer(FocusRingLayerDelegate* delegate,

[xiyuan, 2016/03/22 04:34:27]

nit: explicit not needed when ctor has >1 args.

[dmazzoni, 2016/03/22 20:23:02]

Done.

+                                        int red,
+                                        int green,
+                                        int blue);
+  ~AccessibilityCursorRingLayer() override;
+
+  // Create the layer and update its bounds and position in the hierarchy.
+  void Set(const gfx::Point& location);
+
+  // Set the layer's opacity.
+  void SetOpacity(float opacity);
+
+ private:
+  // ui::LayerDelegate overrides:
+  void OnPaintLayer(const ui::PaintContext& context) override;
+
+  // The current location.
+  gfx::Point location_;
+
+  int red_;
+  int green_;
+  int blue_;
+
+  DISALLOW_COPY_AND_ASSIGN(AccessibilityCursorRingLayer);
+};
+
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_UI_ACCESSIBILITY_CURSOR_RING_LAYER_H_