Show a visual indicator for the progress of auto-click.

chrome/browser/chromeos/ui/autoclick_ring_handler.h

+// Copyright (c) 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_AUTOCLICK_RING_HANDLER_H_
+#define CHROME_BROWSER_CHROMEOS_UI_AUTOCLICK_RING_HANDLER_H_
+
+#include <memory>
+
+#include "ash/autoclick/autoclick_controller.h"
+#include "base/macros.h"
+#include "base/timer/timer.h"
+#include "ui/aura/window_observer.h"
+#include "ui/events/event.h"
+#include "ui/gfx/animation/linear_animation.h"
+#include "ui/gfx/geometry/point.h"
+
+namespace chromeos {
+
+// AutoclickRingHandler displays an animated affordance that is shown
+// on autoclick gesture. The animation sequence consists of two circles which
+// shrink towards the spot the autoclick will generate a mouse event.
+class AutoclickRingHandler : public gfx::LinearAnimation,
+                             public aura::WindowObserver,
+                             public ash::AutoclickController::Delegate {
+ public:
+  AutoclickRingHandler();
+  ~AutoclickRingHandler() override;
+
+ private:
+  // Overriden from ash::AutoclickController::Delegate.
+  void StartGesture(base::TimeDelta duration, gfx::Point center) override;
+  void StopGesture() override;
+  void SetGestureCenter(gfx::Point center) override;
+
+  class AutoclickRingView;
+
+  enum AnimationType {

[oshima, 2016/06/13 21:57:30]

optional: enum class

[sammiequon, 2016/06/15 15:40:53]

Done.

+    NONE,
+    GROW_ANIMATION,
+    SHRINK_ANIMATION,
+  };
+
+  aura::Window* GetTargetWindow();
+  void SetTapDownTarget();
+  void StartAnimation(base::TimeDelta duration);
+  void StopAutoclickRing();
+  void SetTapDownTarget(aura::Window* target);
+
+  // Overridden from gfx::LinearAnimation.
+  void AnimateToState(double state) override;
+  void AnimationStopped() override;
+
+  // Overridden from aura::WindowObserver.
+  void OnWindowDestroying(aura::Window* window) override;
+
+  std::unique_ptr<AutoclickRingView> view_;
+  gfx::Point tap_down_location_;

[oshima, 2016/06/13 21:57:30]

please document the coordinates. 

[sammiequon, 2016/06/15 15:40:53]

Done.

+  aura::Window* tap_down_target_;

[oshima, 2016/06/13 21:57:30]

please document ownership (or lifetime)

[sammiequon, 2016/06/15 15:40:53]

Done.

+  AnimationType current_animation_type_;
+
+  DISALLOW_COPY_AND_ASSIGN(AutoclickRingHandler);
+};
+
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_UI_AUTOCLICK_RING_HANDLER_H_