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

ui/message_center/views/slide_out_controller.h

Index: ui/message_center/views/slide_out_controller.h
diff --git a/ui/message_center/views/slide_out_controller.h b/ui/message_center/views/slide_out_controller.h
new file mode 100644
index 0000000000000000000000000000000000000000..6d7a71c7e3bc0c4fe14cfcf6e5938c75d4202808
--- /dev/null
+++ b/ui/message_center/views/slide_out_controller.h
@@ -0,0 +1,61 @@
+// 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_MESSAGE_CENTER_VIEWS_SLIDE_OUT_CONTROLLER_H_
+#define UI_MESSAGE_CENTER_VIEWS_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 {
+
+// This class contains logic to control sliding out of a layer in response to
+// swipes, i.e. gesture scroll events.
+class SlideOutController : public ui::EventHandler,
+                           public ui::ImplicitAnimationObserver {
+ public:
+  class Delegate {
+   public:
+    // Returns the layer for slide operations.
+    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:
+  // Restores the transform and opacity of the view.
+  void RestoreVisualState();
+
+  // Slides the view out and closes it after the animation. The sign of
+  // |direction| indicates which way the slide occurs.
+  void SlideOutAndClose(int direction);
+
+  ui::ScopedTargetHandler target_handling_;
+  Delegate* delegate_;
+
+  float gesture_amount_ = 0.f;
+  bool enabled_ = true;
+
+  DISALLOW_COPY_AND_ASSIGN(SlideOutController);
+};
+
+}  // namespace views
+
+#endif  // UI_MESSAGE_CENTER_VIEWS_SLIDE_OUT_CONTROLLER_H_