Refactor GestureNavigation to eliminate code redundancy

content/browser/web_contents/aura/overscroll_navigation_overlay.h

 // Copyright 2014 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_NAVIGATION_OVERLAY_H_
 #define CONTENT_BROWSER_WEB_CONTENTS_AURA_OVERSCROLL_NAVIGATION_OVERLAY_H_
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "content/browser/web_contents/aura/window_slider.h"
+#include "content/browser/web_contents/web_contents_view_aura.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/web_contents_observer.h"
+#include "ui/gfx/image/image.h"
 
 struct ViewHostMsg_UpdateRect_Params;
 
 namespace aura_extra {
 class ImageWindowDelegate;
 }
 
 namespace content {
 
 class ImageLayerDelegate;
 class OverscrollNavigationOverlayTest;
 
 // When a history navigation is triggered at the end of an overscroll
 // navigation, it is necessary to show the history-screenshot until the page is
 // done navigating and painting. This class accomplishes this by showing the
 // screenshot window on top of the page until the page has completed loading and
 // painting.
 class CONTENT_EXPORT OverscrollNavigationOverlay
     : public WebContentsObserver,
       public WindowSlider::Delegate {
  public:
-  explicit OverscrollNavigationOverlay(WebContentsImpl* web_contents);
+  // TODO move this somewhere else.
+  enum Direction { FORWARD, BACKWARD, NONE };
+
+  explicit OverscrollNavigationOverlay(WebContentsImpl* web_contents,
+                                       WebContentsViewAura* wcva);
   ~OverscrollNavigationOverlay() override;
 
   bool has_window() const { return !!window_.get(); }
 
   // Resets state and starts observing |web_contents_| for page load/paint
   // updates. This function makes sure that the screenshot window is stacked
   // on top, so that it hides the content window behind it, and destroys the
   // screenshot window when the page is done loading/painting.
   // This should be called immediately after initiating the navigation,
   // otherwise the overlay may be dismissed prematurely.
   void StartObserving();
 
   // Sets the screenshot window and the delegate. This takes ownership of
   // |window|.
   // Note that aura_extra::ImageWindowDelegate manages its own lifetime, so this
   // function does not take ownership of |delegate|.
   void SetOverlayWindow(scoped_ptr<aura::Window> window,
                         aura_extra::ImageWindowDelegate* delegate);
 
+  const gfx::Image GetImageForDirection(Direction direction);
+
+  // Creates a layer with a screenshot for a given direction.
+  scoped_ptr<ui::Layer> CreateLayerForDirection(Direction direction);
+
+  Direction GetNavigationDirection(const NavigationController& controller,
+                                   OverscrollMode mode);
+
  private:
   friend class OverscrollNavigationOverlayTest;
   FRIEND_TEST_ALL_PREFIXES(OverscrollNavigationOverlayTest,
                            FirstVisuallyNonEmptyPaint_NoImage);
   FRIEND_TEST_ALL_PREFIXES(OverscrollNavigationOverlayTest,
                            FirstVisuallyNonEmptyPaint_WithImage);
   FRIEND_TEST_ALL_PREFIXES(OverscrollNavigationOverlayTest,
                            LoadUpdateWithoutNonEmptyPaint);
   FRIEND_TEST_ALL_PREFIXES(OverscrollNavigationOverlayTest,
                            MultiNavigation_LoadingUpdate);
@@ skipping 52 matching lines @@
   // Layer to be used for the final overlay fadeout animation when the overlay
   // is being dismissed.
   scoped_ptr<ui::Layer> overlay_dismiss_layer_;
 
   // The direction of the in-progress slide (if any).
   SlideDirection slide_direction_;
 
   // The LayerDelegate used for the back/front layers during a slide.
   scoped_ptr<ImageLayerDelegate> layer_delegate_;
 
+  // TODO use a delegate.
+  WebContentsViewAura* wcva_;
+
   DISALLOW_COPY_AND_ASSIGN(OverscrollNavigationOverlay);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_WEB_CONTENTS_AURA_OVERSCROLL_NAVIGATION_OVERLAY_H_