Refactor GestureNavigation to eliminate code redundancy

content/browser/web_contents/aura/overscroll_window_animation.h

+// Copyright 2015 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 CONTENT_BROWSER_WEB_CONTENTS_AURA_OVERSCROLL_WINDOW_ANIMATION_H_
+#define CONTENT_BROWSER_WEB_CONTENTS_AURA_OVERSCROLL_WINDOW_ANIMATION_H_
+
+#include "content/browser/renderer_host/overscroll_controller_delegate.h"
+#include "content/common/content_export.h"
+#include "ui/compositor/layer_animation_observer.h"
+
+namespace ui {
+class Layer;
+class LayerAnimator;
+}
+
+namespace content {
+
+class OverscrollLayerWrapper;
+
+// Manages the animations during an overscroll navigation by handling overscroll
+// events.
+class CONTENT_EXPORT OverscrollWindowAnimation
+    : ui::ImplicitAnimationObserver,
+      public OverscrollControllerDelegate {
+ public:
+  enum Direction { FORWARD, BACKWARD, NONE };
+
+  // Delegate class that interfaces with the window animation, responsible for
+  // navigation.
+  class Delegate {
+   public:
+    virtual ~Delegate() {}
+
+    // The following two functions create a layer wrapper and transfer back its
+    // ownership.
+    virtual scoped_ptr<OverscrollLayerWrapper> CreateFrontLayer() = 0;
+    virtual scoped_ptr<OverscrollLayerWrapper> CreateBackLayer() = 0;
+
+    // Called when the animation has been completed. The delagate can then
+    // dismiss the overlay layer, or wait for the page to load first.
+    virtual void OnOverscrollCompleted() = 0;

[mfomitchev, 2015/02/27 21:33:42]

consider passing the scoped ptr to the wrapper here

+
+    // Called when we know the animation is going to complete. This should start
+    // the navigation.
+    virtual void OnOverscrollCompleting() = 0;
+  };
+
+  OverscrollWindowAnimation();
+
+  ~OverscrollWindowAnimation() override;
+
+  // Returns true if there is a slide animation currently in progress.
+  bool is_animation_in_progress() const { return animation_active_; }
+
+  void set_delegate(Delegate* delegate) { delegate_ = delegate; }
+
+  // Overridden from OverscrollControllerDelegate:
+  gfx::Rect GetVisibleBounds() const override;
+
+  bool OnOverscrollUpdate(float delta_x, float delta_y) override;
+
+  void OnOverscrollComplete(OverscrollMode overscroll_mode) override;
+
+  void OnOverscrollModeChange(OverscrollMode old_mode,
+                              OverscrollMode new_mode) override;
+
+ private:
+  // Starts the overscroll cancelled animation.
+  void CancelOverscroll();
+
+  // Moves the animated window according to the given scroll deltas. Returns
+  // true if the update moved the window.
+  bool UpdateForScroll(float delta_x);
+
+  // Returns a translation for the given overscroll.
+  gfx::Vector2dF GetTranslationForOverscroll(float delta_x);
+
+  // Overridden from ui::ImplicitAnimationObserver:
+  void OnImplicitAnimationsCompleted() override;
+
+  // Wrapper that owns the overscroll window.
+  scoped_ptr<OverscrollLayerWrapper> layer_wrapper_;
+
+  // Delegate that provides the animation target and handles navigation.
+  Delegate* delegate_;
+
+  // The current overscroll direction.
+  Direction direction_;
+
+  // True if the overscroll animation is happening right now.
+  bool animation_active_;

[mfomitchev, 2015/02/27 21:33:42]

nit: may be a bit ambiguous: active_ instead of animation_active_? 

[Nina, 2015/03/09 15:54:52]

Done.

+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_WEB_CONTENTS_AURA_OVERSCROLL_WINDOW_ANIMATION_H_