Refactor GestureNavigation to eliminate code redundancy

content/browser/web_contents/aura/overscroll_navigation_overlay.cc

Index: content/browser/web_contents/aura/overscroll_navigation_overlay.cc
diff --git a/content/browser/web_contents/aura/overscroll_navigation_overlay.cc b/content/browser/web_contents/aura/overscroll_navigation_overlay.cc
index a96b0d27ed66cd46912ebc7d55fdee0feb5e9f9c..6c4633e1e832759b1b9d5d49182fdba4511ba144 100644
--- a/content/browser/web_contents/aura/overscroll_navigation_overlay.cc
+++ b/content/browser/web_contents/aura/overscroll_navigation_overlay.cc
@@ -4,8 +4,12 @@
 
 #include "content/browser/web_contents/aura/overscroll_navigation_overlay.h"
 
+#include <vector>
+
 #include "content/browser/frame_host/navigation_entry_impl.h"
 #include "content/browser/renderer_host/render_view_host_impl.h"
+#include "content/browser/web_contents/aura/overscroll_window_delegate.h"
+#include "content/browser/web_contents/aura/slidable_wrapper.h"
 #include "content/browser/web_contents/web_contents_impl.h"
 #include "content/common/view_messages.h"
 #include "content/public/browser/browser_thread.h"
@@ -18,7 +22,6 @@
 #include "ui/compositor/scoped_layer_animation_settings.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/image/image_png_rep.h"
-#include "ui/gfx/image/image_skia.h"
 
 namespace content {
 namespace {
@@ -130,12 +133,16 @@ class OverlayDismissAnimator
 };
 
 OverscrollNavigationOverlay::OverscrollNavigationOverlay(
-    WebContentsImpl* web_contents)
-    : web_contents_(web_contents),
-      image_delegate_(NULL),
+    WebContentsImpl* web_contents,
+    aura::Window* web_contents_window)
+    : direction_(NONE),
+      web_contents_(web_contents),
+      window_(nullptr),
+      image_delegate_(nullptr),
       loading_complete_(false),
       received_paint_update_(false),
-      slide_direction_(SLIDE_UNKNOWN) {
+      owa_(new OverscrollWindowAnimation(this)),
+      web_contents_window_(web_contents_window) {
 }
 
 OverscrollNavigationOverlay::~OverscrollNavigationOverlay() {
@@ -144,13 +151,9 @@ OverscrollNavigationOverlay::~OverscrollNavigationOverlay() {
 void OverscrollNavigationOverlay::StartObserving() {
   loading_complete_ = false;
   received_paint_update_ = false;
-  overlay_dismiss_layer_.reset();
+  dismiss_layer_.reset();
   Observe(web_contents_);
 
-  // Make sure the overlay window is on top.
-  if (window_.get() && window_->parent())
-    window_->parent()->StackChildAtTop(window_.get());
-
   // Assumes the navigation has been initiated.
   NavigationEntry* pending_entry =
       web_contents_->GetController().GetPendingEntry();
@@ -160,140 +163,144 @@ void OverscrollNavigationOverlay::StartObserving() {
   pending_entry_url_ = pending_entry ? pending_entry->GetURL() : GURL();
 }
 
-void OverscrollNavigationOverlay::SetOverlayWindow(
-    scoped_ptr<aura::Window> window,
-    aura_extra::ImageWindowDelegate* delegate) {
-  window_ = window.Pass();
-  if (window_.get() && window_->parent())
-    window_->parent()->StackChildAtTop(window_.get());
-  image_delegate_ = delegate;
-
-  if (window_.get() && delegate->has_image()) {
-    window_slider_.reset(new WindowSlider(this,
-                                          window_->parent(),
-                                          window_.get()));
-    slide_direction_ = SLIDE_UNKNOWN;
-  } else {
-    window_slider_.reset();
-  }
-}
-
 void OverscrollNavigationOverlay::StopObservingIfDone() {
   // Normally we dismiss the overlay once we receive a paint update, however
   // for in-page navigations DidFirstVisuallyNonEmptyPaint() does not get
   // called, and we rely on loading_complete_ for those cases.
-  if (!received_paint_update_ && !loading_complete_)
-    return;
-
   // If a slide is in progress, then do not destroy the window or the slide.
-  if (window_slider_.get() && window_slider_->IsSlideInProgress())
+  if (!window_ ||
+      !(loading_complete_ || received_paint_update_) ||
+      owa_->is_active()) {
     return;
-
-  // The layer to be animated by OverlayDismissAnimator
-  scoped_ptr<ui::Layer> overlay_dismiss_layer;
-  if (overlay_dismiss_layer_)
-    overlay_dismiss_layer = overlay_dismiss_layer_.Pass();
-  else if (window_.get())
-    overlay_dismiss_layer = window_->AcquireLayer();
-  Observe(NULL);
-  window_slider_.reset();
+  }
+  // OverlayDismissAnimator deletes the dismiss layer and itself when the
+  // animation completes.
+  if (!dismiss_layer_)
+    dismiss_layer_ = window_->AcquireLayer();
+  (new OverlayDismissAnimator(dismiss_layer_.Pass()))->Animate();
   window_.reset();
-  image_delegate_ = NULL;
-  if (overlay_dismiss_layer.get()) {
-    // OverlayDismissAnimator deletes overlay_dismiss_layer and itself when the
-    // animation completes.
-    (new OverlayDismissAnimator(overlay_dismiss_layer.Pass()))->Animate();
+  Observe(NULL);
+  received_paint_update_ = false;
+  loading_complete_ = false;
+}
+
+scoped_ptr<SlidableWrapper> OverscrollNavigationOverlay::CreateLayerWrapper() {
+  if (window_) {
+    // This is the second overscroll case, slide a new layer into the overlay
+    // window.
+    if (!layer_delegate_)
+      layer_delegate_.reset(new ImageLayerDelegate());
+    layer_delegate_->SetImage(GetImageForDirection(direction_));
+    scoped_ptr<ui::Layer> layer(new ui::Layer(ui::LAYER_TEXTURED));
+    layer->set_delegate(layer_delegate_.get());
+    ui::Layer* parent = window_->layer()->parent();
+    parent->Add(layer.get());
+    if (direction_ == FORWARD)
+      parent->StackAbove(layer.get(), window_->layer());
+    else
+      parent->StackBelow(layer.get(), window_->layer());
+    // Destroy the dismiss layer as it may hide the newly created layers.
+    dismiss_layer_.reset();
+    return scoped_ptr<SlidableWrapper>(
+        new SlidableWrapper(layer.Pass()));
+  }
+  // The user has just started the overscroll. Create the overlay window and
+  // pass it in a SlidableWrapper.
+  image_delegate_ =
+      new OverscrollWindowDelegate(owa_.get(),
+                                   GetImageForDirection(direction_));
+  scoped_ptr<aura::Window> window(new aura::Window(image_delegate_));
+  window->SetTransparent(true);
+  window->Init(aura::WINDOW_LAYER_TEXTURED);
+  window->layer()->SetMasksToBounds(false);
+  window->SetName("OverscrollOverlay");
+  web_contents_window_->AddChild(window.get());
+  window->Show();
+  if (direction_ == FORWARD) {
+    web_contents_window_->StackChildAbove(
+        window.get(), web_contents_->GetContentNativeView());
+  } else {
+    web_contents_window_->StackChildBelow(
+        window.get(), web_contents_->GetContentNativeView());
   }
+  return scoped_ptr<SlidableWrapper>(
+      new SlidableWrapper(window.Pass()));
 }
 
-ui::Layer* OverscrollNavigationOverlay::CreateSlideLayer(int offset) {
+const gfx::Image OverscrollNavigationOverlay::GetImageForDirection(
+    NavigationDirection direction) const {
   const NavigationControllerImpl& controller = web_contents_->GetController();
-  const NavigationEntryImpl* entry = controller.GetEntryAtOffset(offset);
+  const NavigationEntryImpl* entry = NavigationEntryImpl::FromNavigationEntry(
+      controller.GetEntryAtOffset(direction == FORWARD ? 1 : -1));
 
-  gfx::Image image;
   if (entry && entry->screenshot().get()) {
     std::vector<gfx::ImagePNGRep> image_reps;
     image_reps.push_back(gfx::ImagePNGRep(entry->screenshot(), 1.0f));
-    image = gfx::Image(image_reps);
+    return gfx::Image(image_reps);
   }
-  if (!layer_delegate_)
-    layer_delegate_.reset(new ImageLayerDelegate());
-  layer_delegate_->SetImage(image);
+  return gfx::Image();
+}
 
-  ui::Layer* layer = new ui::Layer(ui::LAYER_TEXTURED);
-  layer->set_delegate(layer_delegate_.get());
-  return layer;
+scoped_ptr<SlidableWrapper> OverscrollNavigationOverlay::CreateFrontWrapper() {
+  if (!web_contents_->GetController().CanGoForward())
+    return nullptr;
+  direction_ = FORWARD;
+  return CreateLayerWrapper();
 }
 
-ui::Layer* OverscrollNavigationOverlay::CreateBackLayer() {
+scoped_ptr<SlidableWrapper> OverscrollNavigationOverlay::CreateBackWrapper() {
   if (!web_contents_->GetController().CanGoBack())
-    return NULL;
-  slide_direction_ = SLIDE_BACK;
-  return CreateSlideLayer(-1);
+    return nullptr;
+  direction_ = BACK;
+  return CreateLayerWrapper();
 }
 
-ui::Layer* OverscrollNavigationOverlay::CreateFrontLayer() {
-  if (!web_contents_->GetController().CanGoForward())
-    return NULL;
-  slide_direction_ = SLIDE_FRONT;
-  return CreateSlideLayer(1);
+aura::Window* OverscrollNavigationOverlay::GetTargetWindow() const {
+  if (window_)
+    return window_.get();
+  return web_contents_->GetContentNativeView();
 }
 
-void OverscrollNavigationOverlay::OnWindowSlideCompleting() {
-  if (slide_direction_ == SLIDE_UNKNOWN)
-    return;
-
-  // Perform the navigation.
-  if (slide_direction_ == SLIDE_BACK)
-    web_contents_->GetController().GoBack();
-  else if (slide_direction_ == SLIDE_FRONT)
+void OverscrollNavigationOverlay::OnOverscrollCompleting() {
+  // We start the navigation as soon as we know the overscroll gesture is
+  // completing.
+  DCHECK(direction_ != NONE);
+  // Make sure we can navigate first, as other factors can trigger a navigation
+  // during an overscroll gesture and navigating without history produces a
+  // crash.
+  if (direction_ == FORWARD && web_contents_->GetController().CanGoForward())
     web_contents_->GetController().GoForward();
-  else
-    NOTREACHED();
-
-  // Reset state and wait for the new navigation page to complete
-  // loading/painting.
+  if (direction_ == BACK && web_contents_->GetController().CanGoBack())
+    web_contents_->GetController().GoBack();
   StartObserving();
 }
 
-void OverscrollNavigationOverlay::OnWindowSlideCompleted(
-    scoped_ptr<ui::Layer> layer) {
-  if (slide_direction_ == SLIDE_UNKNOWN) {
-    window_slider_.reset();
-    StopObservingIfDone();
-    return;
+void OverscrollNavigationOverlay::OnOverscrollCompleted(
+    scoped_ptr<SlidableWrapper> wrapper) {
+  if (!window_) {
+    DCHECK(wrapper->has_window());
+    window_ = wrapper->AcquireWindow();
+    // Make sure the overlay window is on top.
+    web_contents_window_->StackChildAtTop(window_.get());
+    // Reset the position of the contents window.
+    web_contents_->GetContentNativeView()->SetTransform(gfx::Transform());
+  } else {
+    dismiss_layer_ = wrapper->AcquireLayer();
+    // Change the image used for the overlay window.
+    image_delegate_->SetImage(layer_delegate_->image());
+    // Reset the position of its layer.
+    window_->layer()->SetTransform(gfx::Transform());
+    window_->SchedulePaintInRect(gfx::Rect(window_->bounds().size()));
   }
-
-  // Change the image used for the overlay window.
-  image_delegate_->SetImage(layer_delegate_->image());
-  window_->layer()->SetTransform(gfx::Transform());
-  window_->SchedulePaintInRect(gfx::Rect(window_->bounds().size()));
-  slide_direction_ = SLIDE_UNKNOWN;
-  // We may end up dismissing the overlay before it has a chance to repaint, so
-  // set the slider layer to be the one animated by OverlayDismissAnimator.
-  if (layer.get())
-    overlay_dismiss_layer_ = layer.Pass();
+  direction_ = NONE;
   StopObservingIfDone();
 }
 
-void OverscrollNavigationOverlay::OnWindowSlideAborted() {
+void OverscrollNavigationOverlay::OnOverscrollAborted() {
+  direction_ = NONE;
   StopObservingIfDone();
 }
 
-void OverscrollNavigationOverlay::OnWindowSliderDestroyed() {
-  // We only want to take an action here if WindowSlider is being destroyed
-  // outside of OverscrollNavigationOverlay. If window_slider_.get() is NULL,
-  // then OverscrollNavigationOverlay is the one destroying WindowSlider, and
-  // we don't need to do anything.
-  // This check prevents StopObservingIfDone() being called multiple times
-  // (including recursively) for a single event.
-  if (window_slider_.get()) {
-    // The slider has just been destroyed. Release the ownership.
-    ignore_result(window_slider_.release());
-    StopObservingIfDone();
-  }
-}
-
 void OverscrollNavigationOverlay::DidFirstVisuallyNonEmptyPaint() {
   NavigationEntry* visible_entry =
       web_contents_->GetController().GetVisibleEntry();