CrOS: Fix appearance of notification toasts when sliding out via gesture

ui/views/controls/slide_out_controller.h

Index: ui/views/controls/slide_out_controller.h
diff --git a/ui/views/controls/slide_out_controller.h b/ui/views/controls/slide_out_controller.h
new file mode 100644
index 0000000000000000000000000000000000000000..e5bbaf45cb60111b1f0bd97e2f14b7eedf781e31
--- /dev/null
+++ b/ui/views/controls/slide_out_controller.h
@@ -0,0 +1,64 @@
+// Copyright (c) 2012 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 UI_VIEWS_CONTROLS_SLIDE_OUT_CONTROLLER_H_
+#define UI_VIEWS_CONTROLS_SLIDE_OUT_CONTROLLER_H_
+
+#include "base/macros.h"
+#include "ui/compositor/layer_animation_observer.h"
+#include "ui/events/scoped_target_handler.h"
+#include "ui/views/view.h"
+#include "ui/views/views_export.h"
+
+namespace views {
+
+// A View that can be closed by a slide-out touch gesture.

[sky, 2017/04/28 22:35:36]

Please update description.

[Evan Stade, 2017/04/28 23:18:38]

Done.

+class VIEWS_EXPORT SlideOutController : public ui::EventHandler,

[sky, 2017/04/28 22:35:36]

I would prefer this code move to where it is used, which is in messagecenter.

[Evan Stade, 2017/04/28 23:18:38]

Done.

+                                        public ui::ImplicitAnimationObserver {
+ public:
+  class Delegate {
+   public:
+    // Returns the layer to for slide operations.

[sky, 2017/04/28 22:35:36]

'to for' -> 'for' ?

[Evan Stade, 2017/04/28 23:18:38]

Done.

+    virtual ui::Layer* GetSlideOutLayer() = 0;
+
+    // Called when user intends to close the View by sliding it out.
+    virtual void OnSlideOut() = 0;
+  };
+
+  SlideOutController(ui::EventTarget* target, Delegate* delegate);
+  ~SlideOutController() override;
+
+  void set_enabled(bool enabled) { enabled_ = enabled; }
+  bool enabled() { return enabled_; }
+
+  // ui::EventHandler
+  void OnGestureEvent(ui::GestureEvent* event) override;
+
+  // ui::ImplicitAnimationObserver
+  void OnImplicitAnimationsCompleted() override;
+
+ private:
+  enum SlideDirection {

[sky, 2017/04/28 22:35:36]

enum class?

[Evan Stade, 2017/04/28 23:18:38]

removed this.

+    SLIDE_LEFT,
+    SLIDE_RIGHT,
+  };
+
+  // Restores the transform and opacity of the view.
+  void RestoreVisualState();
+
+  // Slides the view out and closes it after the animation.
+  void SlideOutAndClose(SlideDirection direction);
+
+  ui::ScopedTargetHandler target_handling_;
+  Delegate* delegate_;
+
+  float gesture_amount_ = 0.f;
+  bool enabled_ = true;
+
+  DISALLOW_COPY_AND_ASSIGN(SlideOutController);
+};
+
+}  // namespace views
+
+#endif  // UI_VIEWS_CONTROLS_SLIDE_OUT_CONTROLLER_H_