Refactor GestureNavigation to eliminate code redundancy

content/browser/web_contents/aura/overscroll_navigation_overlay.h

Index: content/browser/web_contents/aura/overscroll_navigation_overlay.h
diff --git a/content/browser/web_contents/aura/overscroll_navigation_overlay.h b/content/browser/web_contents/aura/overscroll_navigation_overlay.h
index db9871c024981ff908b20bfd9b2ed1baddcc6eaa..628d790e5f043edab13021ec65e58d8d94248abb 100644
--- a/content/browser/web_contents/aura/overscroll_navigation_overlay.h
+++ b/content/browser/web_contents/aura/overscroll_navigation_overlay.h
@@ -7,9 +7,11 @@
 
 #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;
 
@@ -20,6 +22,7 @@ class ImageWindowDelegate;
 namespace content {
 
 class ImageLayerDelegate;
+class OverscrollWindowDelegate;
 class OverscrollNavigationOverlayTest;
 
 // When a history navigation is triggered at the end of an overscroll
@@ -29,27 +32,16 @@ class OverscrollNavigationOverlayTest;
 // painting.
 class CONTENT_EXPORT OverscrollNavigationOverlay
     : public WebContentsObserver,
-      public WindowSlider::Delegate {
+      public OverscrollWindowAnimation::Delegate {
  public:
-  explicit OverscrollNavigationOverlay(WebContentsImpl* web_contents);
-  ~OverscrollNavigationOverlay() override;
+  enum Direction { FORWARD, BACK, NONE };

[mfomitchev, 2015/03/10 19:26:00]

Maybe call this NavigastionDirection, and the one in OWA - SlideDirection to
reduce the risk of confusion

[Nina, 2015/03/12 22:21:29]

Done.

 
-  bool has_window() const { return !!window_.get(); }
+  OverscrollNavigationOverlay(WebContentsImpl* web_contents,
+                              aura::Window* web_contents_window);
 
-  // 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();
+  ~OverscrollNavigationOverlay() override;
 
-  // 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);
+  //OverscrollWindowAnimation::Direction direction() { return direction_; }
 
  private:
   friend class OverscrollNavigationOverlayTest;
@@ -64,40 +56,59 @@ class CONTENT_EXPORT OverscrollNavigationOverlay
   FRIEND_TEST_ALL_PREFIXES(OverscrollNavigationOverlayTest,
                            MultiNavigation_PaintUpdate);
 
-  enum SlideDirection {
-    SLIDE_UNKNOWN,
-    SLIDE_BACK,
-    SLIDE_FRONT
-  };
+  // 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();
 
   // 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.
   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 the overscroll window if it does not exist or layer if it does,
+  // wraps it and transfers its ownership.
+  scoped_ptr<OverscrollLayerWrapper> CreateLayerWrapper();
+
+  // Creates the overlay window and transfers its ownership to the caller.
+  scoped_ptr<aura::Window> CreateOverlayWindow();
+
+  // Creates a layer to slide on top of the overscroll window.
+  scoped_ptr<ui::Layer> CreateSlideLayer();
 
-  // 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;
+  // Fades out the overscroll window and dismisses it.
+  void FadeOutOverscrollWindow();
+
+  // Returns the screenshot for the given direction.
+  const gfx::Image GetImageForDirection(Direction direction) const;
+
+  // Overridden from OverscrollWindowAnimation::Delegate:
+  scoped_ptr<OverscrollLayerWrapper> CreateFrontLayerWrapper() override;
+  scoped_ptr<OverscrollLayerWrapper> CreateBackLayerWrapper() override;
+  void OnOverscrollCompleting() override;
+  void OnOverscrollCompleted(
+      scoped_ptr<OverscrollLayerWrapper> layer_wrapper) override;
+  void OnOverscrollAborted() override;
 
   // Overridden from WebContentsObserver:
   void DidFirstVisuallyNonEmptyPaint() override;
   void DidStopLoading(RenderViewHost* host) override;
 
-  // The WebContents which is being navigated.
+  // The current overscroll direction.
+  Direction direction_;
+
+  // The web contents that are being navigated.
   WebContentsImpl* web_contents_;
 
-  // The screenshot overlay window.
+  // This window shows a screenshot during an overscroll gesture and hosts the
+  // delegate that processes overscroll events right after a successfull

[mfomitchev, 2015/03/10 19:26:00]

I don't think you need to talk about the delegate here - it's irrelevant in the
context of ONO. I.e. we can change the way events are delivered to/processed in
OWA, and ideally it shouldn't change ONO (including the comments in ONO) in any
way.

[Nina, 2015/03/12 22:21:29]

Done.

+  // overscroll navigation.
   scoped_ptr<aura::Window> window_;
 
-  // This is the WindowDelegate of |window_|. The delegate manages its own
+  // This is the WindowDelegate of |window_|. The delegates manages its own
   // lifetime (destroys itself when |window_| is destroyed).
   aura_extra::ImageWindowDelegate* image_delegate_;
 
@@ -109,20 +120,19 @@ class CONTENT_EXPORT OverscrollNavigationOverlay
   // 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_;
+  // We own the OWA instance that handles layer animations for the case where an

[mfomitchev, 2015/03/10 19:26:00]

..for the case where an overscroll gesture occurs while an overscroll overlay is
displayed waiting for the page to load before it is dismissed.

[Nina, 2015/03/12 22:21:29]

Changed the comment.

+  // overscroll gesture quickly follows another one.
+  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 window that hosts the web contents.
+  aura::Window* web_contents_window_;
 
   // The LayerDelegate used for the back/front layers during a slide.
   scoped_ptr<ImageLayerDelegate> layer_delegate_;
 
+  // The layer schedule to dismiss.
+  scoped_ptr<ui::Layer> dismiss_layer_;

[mfomitchev, 2015/03/16 22:28:01]

We should confirm if this is not needed before removing it. The question we need
to ask is if we have layer1, change it's contents, schedule a repaint, and then
remove layer2 which is on top of layer1 - are we guaranteed that we won't see
layer1 with the old contents.

[Nina, 2015/03/17 14:27:07]

Ah, I saw the flickering we discussed today. I'll try to make it work by
resetting the dismiss layer when a new layer is created.

+
   DISALLOW_COPY_AND_ASSIGN(OverscrollNavigationOverlay);
 };