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/aura/overscroll_window_animation.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 OverscrollWindowDelegate;
 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.
+// done navigating and painting. This class accomplishes this by calling the
+// navigation and creating, showing and destroying 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 OverscrollWindowAnimation::Delegate {
  public:
-  explicit OverscrollNavigationOverlay(WebContentsImpl* web_contents);
+  enum NavigationDirection { FORWARD, BACK, NONE };
+
+  OverscrollNavigationOverlay(WebContentsImpl* web_contents,
+                              aura::Window* web_contents_window);
+
   ~OverscrollNavigationOverlay() override;
 
-  bool has_window() const { return !!window_.get(); }
+  // Returns a pointer to the overscroll window animation we own.
+  OverscrollWindowAnimation* owa() { return owa_.get(); }
+
+ private:
+  friend class OverscrollNavigationOverlayTest;
+  FRIEND_TEST_ALL_PREFIXES(OverscrollNavigationOverlayTest, WithScreenshot);
+  FRIEND_TEST_ALL_PREFIXES(OverscrollNavigationOverlayTest, WithoutScreenshot);
+  FRIEND_TEST_ALL_PREFIXES(OverscrollNavigationOverlayTest, CannotNavigate);
+  FRIEND_TEST_ALL_PREFIXES(OverscrollNavigationOverlayTest, AbortNavigation);
+  FRIEND_TEST_ALL_PREFIXES(OverscrollNavigationOverlayTest,
+                           AbortAfterSuccessfulNavigation);
+  FRIEND_TEST_ALL_PREFIXES(OverscrollNavigationOverlayTest, OverlayWindowSwap);
 
   // 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);
-
- 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);
-  FRIEND_TEST_ALL_PREFIXES(OverscrollNavigationOverlayTest,
-                           MultiNavigation_PaintUpdate);
-
-  enum SlideDirection {
-    SLIDE_UNKNOWN,
-    SLIDE_BACK,
-    SLIDE_FRONT
-  };
-
   // Stop observing the page and start the final overlay fade-out animation if
-  // a window-slide isn't in progress and either the page has been painted or
-  // the page-load has completed.
+  // an overscroll slide isn't in progress and either the page has been painted

[mfomitchev, 2015/03/31 21:04:06]

I don't think "overscroll slide" hasn't been established as a term in this
class. Either explain what it is or just say "if there's no active overscroll
window animation".

[Nina, 2015/04/01 18:10:01]

Done.

+  // or the page-load has completed.
   void StopObservingIfDone();
 
-  // Creates a layer to be used for window-slide. |offset| is the offset of the
-  // NavigationEntry for the screenshot image to display.
-  ui::Layer* CreateSlideLayer(int offset);
+  // Creates a window that shows a history-screenshot and is stacked relative to
+  // the current overscroll |direction_|. Transfers ownership to the caller.

[mfomitchev, 2015/03/31 21:04:06]

NO need to talk about the ownership transfer. scoped_ptr makes the ownership
clear.

[Nina, 2015/04/01 18:10:01]

Removed.

+  scoped_ptr<aura::Window> CreateOverlayWindow();
 
-  // Overridden from WindowSlider::Delegate:
-  ui::Layer* CreateBackLayer() override;
-  ui::Layer* CreateFrontLayer() override;
-  void OnWindowSlideCompleting() override;
-  void OnWindowSlideCompleted(scoped_ptr<ui::Layer> layer) override;
-  void OnWindowSlideAborted() override;
-  void OnWindowSliderDestroyed() override;
+  // Returns an image with the history-screenshot for the previous or next page,
+  // according to the given |direction|.
+  const gfx::Image GetImageForDirection(NavigationDirection direction) const;
+
+  // Overridden from OverscrollWindowAnimation::Delegate:
+  scoped_ptr<aura::Window> CreateFrontWindow() override;
+  scoped_ptr<aura::Window> CreateBackWindow() override;
+  aura::Window* GetMainWindow() const override;
+  void OnOverscrollCompleting() override;
+  void OnOverscrollCompleted(scoped_ptr<aura::Window> window) override;
+  void OnOverscrollAborted() override;
 
   // Overridden from WebContentsObserver:
   void DidFirstVisuallyNonEmptyPaint() override;
   void DidStopLoading() override;
 
-  // The WebContents which is being navigated.
+  // The current overscroll direction.
+  NavigationDirection direction_;
+
+  // The web contents that are being navigated.
   WebContentsImpl* web_contents_;
 
-  // The screenshot overlay window.
+  // The overlay window that shows a screenshot during an overscroll gesture and
+  // handles overscroll events.
   scoped_ptr<aura::Window> window_;

[mfomitchev, 2015/03/31 21:04:06]

Now this is actually a bit misleading since this is null in the "first case" and
is only set to the overlay window in the "second case". To explain this field we
need to explain these two cases somewhere in this .h. Perhaps right here or in
the class comments.

[Nina, 2015/04/01 18:10:01]

Explained up there in the class comments.

 
-  // This is the WindowDelegate of |window_|. The delegate manages its own
-  // lifetime (destroys itself when |window_| is destroyed).
-  aura_extra::ImageWindowDelegate* image_delegate_;
-
   bool loading_complete_;
   bool received_paint_update_;
 
   // URL of the NavigationEntry we are navigating to. This is needed to
   // filter on WebContentsObserver callbacks and is used to dismiss the overlay
   // when the relevant page loads and paints.
   GURL pending_entry_url_;
 
-  // The |WindowSlider| that allows sliding history layers while the page is
-  // being reloaded.
-  scoped_ptr<WindowSlider> window_slider_;
+  // Manages the overscroll animations.
+  scoped_ptr<OverscrollWindowAnimation> owa_;
 
-  // 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_;
+  // The window that hosts the web contents.
+  aura::Window* web_contents_window_;
 
   DISALLOW_COPY_AND_ASSIGN(OverscrollNavigationOverlay);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_WEB_CONTENTS_AURA_OVERSCROLL_NAVIGATION_OVERLAY_H_