Palette tool laser prototype.

ash/common/system/chromeos/palette/tools/laser_pointer_mode.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 ASH_COMMON_SYSTEM_CHROMEOS_PALETTE_TOOLS_LASER_POINTER_MODE_H_
+#define ASH_COMMON_SYSTEM_CHROMEOS_PALETTE_TOOLS_LASER_POINTER_MODE_H_
+
+#include "ash/common/system/chromeos/palette/common_palette_tool.h"
+#include "ui/views/pointer_watcher.h"
+
+namespace ash {
+
+class LaserPointerView;
+
+// Controller for the laser pointer functionality. Enables/disables laser
+// pointer as well as receives points and passes them off to be rendered.
+class LaserPointerMode : public CommonPaletteTool,
+                         public views::PointerWatcher {
+ public:
+  explicit LaserPointerMode(Delegate* delegate);
+  ~LaserPointerMode() override;
+
+ private:
+  friend class LaserPointerModeTestApi;
+
+  // PaletteTool:
+  PaletteGroup GetGroup() const override;
+  PaletteToolId GetToolId() const override;
+  void OnEnable() override;
+  void OnDisable() override;
+  gfx::VectorIconId GetActiveTrayIcon() override;
+  views::View* CreateView() override;
+
+  // CommonPaletteTool:
+  gfx::VectorIconId GetPaletteIconId() override;
+
+  // views::PointerWatcher:
+  void OnPointerEventObserved(const ui::PointerEvent& event,
+                              const gfx::Point& location_in_screen,
+                              views::Widget* target) override;
+
+  void StopTimer();
+
+  // Timer callback which adds a point where the mouse was last seen. This
+  // allows the trail to fade away when the mouse is stationary.
+  void AddStationaryPoint();
+
+  // Timer which will add a new stationary point when the mouse stops moving.
+  // This will remove points past a certain threshold.

[jdufault, 2016/08/19 21:05:56]

Instead of "threshold", what about "too old"?

[sammiequon, 2016/08/22 18:07:19]

Done.

+  std::unique_ptr<base::Timer> timer_;
+  int timer_repeat_count_ = 0;
+
+  gfx::Point current_mouse_location_;
+  std::unique_ptr<LaserPointerView> laser_pointer_view_;
+
+  DISALLOW_COPY_AND_ASSIGN(LaserPointerMode);
+};
+
+}  // namespace ash
+
+#endif  // ASH_COMMON_SYSTEM_CHROMEOS_PALETTE_TOOLS_LASER_POINTER_MODE_H_