Keep dedicated layers for hiding animation

ui/views/corewm/window_animations.cc

Index: ui/views/corewm/window_animations.cc
diff --git a/ui/views/corewm/window_animations.cc b/ui/views/corewm/window_animations.cc
index 42b26413129abdd166b339cd15de902c2393946e..f2da98a837d592da262b9223caeade9094008419 100644
--- a/ui/views/corewm/window_animations.cc
+++ b/ui/views/corewm/window_animations.cc
@@ -107,31 +107,22 @@ int GetWindowVisibilityAnimationType(aura::Window* window) {
   return type;
 }
 
-// Observes a hide animation.
-// A window can be hidden for a variety of reasons. Sometimes, Hide() will be
-// called and life is simple. Sometimes, the window is actually bound to a
-// views::Widget and that Widget is closed, and life is a little more
-// complicated. When a Widget is closed the aura::Window* is actually not
-// destroyed immediately - it is actually just immediately hidden and then
-// destroyed when the stack unwinds. To handle this case, we start the hide
-// animation immediately when the window is hidden, then when the window is
-// subsequently destroyed this object acquires ownership of the window's layer,
-// so that it can continue animating it until the animation completes.
-// Regardless of whether or not the window is destroyed, this object deletes
-// itself when the animation completes.
+// A base class for hiding animation observer. This calls
+// AnimationHost::OnWindowHidingAnimationCompleted upon completion.
 class HidingWindowAnimationObserver : public ui::ImplicitAnimationObserver,
                                       public aura::WindowObserver {
  public:
-  explicit HidingWindowAnimationObserver(aura::Window* window)
+  HidingWindowAnimationObserver(aura::Window* window,
+                                ui::ScopedLayerAnimationSettings* settings)
       : window_(window) {
-    window_->AddObserver(this);
+    window->AddObserver(this);
+    if (settings)
+      settings->AddObserver(this);
   }
+
   virtual ~HidingWindowAnimationObserver() {
-    STLDeleteElements(&layers_);
   }
 
- private:
-  // Overridden from ui::ImplicitAnimationObserver:
   virtual void OnImplicitAnimationsCompleted() OVERRIDE {
     // Window may have been destroyed by this point.
     if (window_) {
@@ -144,30 +135,122 @@ class HidingWindowAnimationObserver : public ui::ImplicitAnimationObserver,
     delete this;
   }
 
+  virtual void OnWindowDestroying(aura::Window* window) OVERRIDE {
+    DCHECK_EQ(window, window_);
+    window_->RemoveObserver(this);
+    window_ = NULL;
+  }
+
+ protected:
+  aura::Window* window_;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(HidingWindowAnimationObserver);
+};
+
+// A window can be hidden for a variety of reasons. Sometimes, Hide() will be
+// called and life is simple. Sometimes, the window is actually bound to a
+// views::Widget and that Widget is closed, and life is a little more
+// complicated. When a Widget is closed the aura::Window* is actually not
+// destroyed immediately - it is actually just immediately hidden and then
+// destroyed when the stack unwinds. To handle this case, we start the hide
+// animation immediately when the window is hidden, then when the window is
+// subsequently destroyed this object acquires ownership of the window's layer,
+// so that it can continue animating it until the animation completes.
+// Regardless of whether or not the window is destroyed, this object deletes
+// itself when the animation completes.
+class DetachLayersWhenDestroyedAnimationObserver
+    : public HidingWindowAnimationObserver {
+ public:
+  DetachLayersWhenDestroyedAnimationObserver(
+      aura::Window* window,
+      ui::ScopedLayerAnimationSettings* settings)
+      : HidingWindowAnimationObserver(window, settings) {
+  }
+
+  virtual ~DetachLayersWhenDestroyedAnimationObserver() {
+    STLDeleteElements(&layers_);
+  }
+
+ private:
   // Overridden from aura::WindowObserver:
   virtual void OnWindowDestroying(aura::Window* window) OVERRIDE {
     DCHECK_EQ(window, window_);
     DCHECK(layers_.empty());
     AcquireAllLayers(window_->layer());
-    window_->RemoveObserver(this);
-    window_ = NULL;
+    HidingWindowAnimationObserver::OnWindowDestroying(window);
   }
 
   void AcquireAllLayers(ui::Layer* layer) {
     if (layer->owner()) {
       ui::Layer* released = layer->owner()->AcquireLayer();
-      DCHECK_EQ(layer, released);
+      CHECK_EQ(layer, released);
       layers_.push_back(released);
     }
-    std::vector<Layer*>::const_iterator it = layer->children().begin();
+    std::vector<ui::Layer*>::const_iterator it = layer->children().begin();
     for (; it != layer->children().end(); ++it)
       AcquireAllLayers(*it);
   }
 
-  aura::Window* window_;
   std::vector<ui::Layer*> layers_;
 
-  DISALLOW_COPY_AND_ASSIGN(HidingWindowAnimationObserver);
+  DISALLOW_COPY_AND_ASSIGN(DetachLayersWhenDestroyedAnimationObserver);
+};
+
+// When hiding an active window, the animating layer can be hidden by
+// new active window's layer. This class detaches the layers for
+// hiding animation, creates new layers for the window and stacks them
+// above the window and its transient children so that the layer for
+// new active window will not hide the hiding animation.
+class DetachAndRecreateLayersAnimationObserver
+    : HidingWindowAnimationObserver {
+ public:
+  DetachAndRecreateLayersAnimationObserver(
+      aura::Window* window,
+      ui::ScopedLayerAnimationSettings* settings)
+      : HidingWindowAnimationObserver(window, settings) {
+  }
+
+  virtual ~DetachAndRecreateLayersAnimationObserver() {
+    DeepDeleteLayers(layer_);
+  }
+
+  void DetachAndRecreateLayers() {
+    layer_ = RecreateWindowLayers(window_, true);
+    // If the window has transient children, move above the top most
+    // transient child so that activation change does not put the
+    // window above the animating layer.
+    if(window_->parent()) {
+      const aura::Window::Windows& transient_children =
+          GetTransientChildren(window_);
+      aura::Window::Windows::const_iterator iter =
+          std::find(window_->parent()->children().begin(),
+                    window_->parent()->children().end(),
+                    window_);
+      DCHECK(iter != window_->parent()->children().end());
+      aura::Window* topmost_transient_child = NULL;
+      for (++iter; iter != window_->parent()->children().end(); ++iter) {
+        if (std::find(transient_children.begin(),
+                      transient_children.end(),
+                      *iter) !=
+            transient_children.end()) {
+          topmost_transient_child = *iter;
+        }
+      }
+      if (topmost_transient_child) {
+        window_->parent()->layer()->StackAbove(
+            layer_, topmost_transient_child->layer());
+      }
+    }
+    // Make the new layer invisible immediately.
+    window_->layer()->SetVisible(false);
+    window_->layer()->SetOpacity(0);
+  }
+
+ private:
+  ui::Layer* layer_;
+
+  DISALLOW_COPY_AND_ASSIGN(DetachAndRecreateLayersAnimationObserver);
 };
 
 void GetTransformRelativeToRoot(ui::Layer* layer, gfx::Transform* transform) {
@@ -255,7 +338,8 @@ void AnimateHideWindowCommon(aura::Window* window,
 
   // Property sets within this scope will be implicitly animated.
   ui::ScopedLayerAnimationSettings settings(window->layer()->GetAnimator());
-  settings.AddObserver(new HidingWindowAnimationObserver(window));
+  scoped_ptr<LayerDetacherForHidingAnimation> detacher =
+      DetachAndRecreateLayersForHidingAnimation(window, &settings);
 
   base::TimeDelta duration = GetWindowVisibilityAnimationDuration(*window);
   if (duration.ToInternalValue() > 0)
@@ -358,8 +442,11 @@ void AddLayerAnimationsForRotate(aura::Window* window, bool show) {
   base::TimeDelta duration = base::TimeDelta::FromMilliseconds(
       kWindowAnimation_Rotate_DurationMS);
 
+  scoped_ptr<LayerDetacherForHidingAnimation> layer_detacher;
   if (!show) {
-    new HidingWindowAnimationObserver(window);
+    // TODO(oshima): Fix observer leak.
+    layer_detacher =
+        DetachAndRecreateLayersForHidingAnimation(window, NULL).Pass();
     window->layer()->GetAnimator()->SchedulePauseForProperties(
         duration * (100 - kWindowAnimation_Rotate_OpacityDurationPercent) / 100,
         ui::LayerAnimationElement::OPACITY);
@@ -477,6 +564,28 @@ bool AnimateHideWindow(aura::Window* window) {
   }
 }
 
+// Refer to the description of LayerDetacherForHidingAnimation in
+// window_animations.h for details.
+class LayerDetacherForHidingAnimationImpl
+    : public LayerDetacherForHidingAnimation {
+ public:
+  LayerDetacherForHidingAnimationImpl(
+      aura::Window* window,
+      ui::ScopedLayerAnimationSettings* settings)
+    : observer_(
+          new DetachAndRecreateLayersAnimationObserver(window, settings)) {
+  }
+
+  virtual ~LayerDetacherForHidingAnimationImpl() {
+    observer_->DetachAndRecreateLayers();
+  }
+
+ private:
+  DetachAndRecreateLayersAnimationObserver* observer_;
+
+  DISALLOW_COPY_AND_ASSIGN(LayerDetacherForHidingAnimationImpl);
+};
+
 }  // namespace
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -521,9 +630,18 @@ void SetWindowVisibilityAnimationVerticalPosition(aura::Window* window,
   window->SetProperty(kWindowVisibilityAnimationVerticalPositionKey, position);
 }
 
-ui::ImplicitAnimationObserver* CreateHidingWindowAnimationObserver(
-    aura::Window* window) {
-  return new HidingWindowAnimationObserver(window);
+scoped_ptr<LayerDetacherForHidingAnimation>
+DetachAndRecreateLayersForHidingAnimation(
+    aura::Window* window,
+    ui::ScopedLayerAnimationSettings* settings) {
+  return scoped_ptr<LayerDetacherForHidingAnimation>(
+      new LayerDetacherForHidingAnimationImpl(window, settings)).Pass();
+}
+
+void DetachLayersForHidingAnimationWhenDestroyed(
+    aura::Window* window,
+    ui::ScopedLayerAnimationSettings* settings) {
+  new DetachLayersWhenDestroyedAnimationObserver(window, settings);
 }
 
 bool AnimateOnChildWindowVisibilityChanged(aura::Window* window, bool visible) {