Rework View Layer Draw() to use the Layer::DrawTree() method and the LayerDelegate.

aura/window.cc

Index: aura/window.cc
===================================================================
--- aura/window.cc	(revision 100773)
+++ aura/window.cc	(working copy)
@@ -54,7 +54,8 @@
     return;
 
   visibility_ = visibility;
-  if (visibility_ != VISIBILITY_HIDDEN)
+  layer_->set_visible(visibility_ != VISIBILITY_HIDDEN);
+  if (layer_->visible())
     SchedulePaint();
 }
 
@@ -105,12 +106,6 @@
   SchedulePaintInRect(gfx::Rect());
 }
 
-void Window::DrawTree() {
-  Draw();
-  for (Windows::iterator i = children_.begin(); i != children_.end(); ++i)
-    (*i)->DrawTree();
-}
-
 void Window::AddChild(Window* child) {
   DCHECK(std::find(children_.begin(), children_.end(), child) ==
       children_.end());
@@ -168,17 +163,13 @@
   return parent_ ? parent_->GetFocusManager() : NULL;
 }
 
-void Window::Draw() {
-  if (visibility_ != VISIBILITY_HIDDEN)
-    layer_->Draw();
-}
-
 void Window::SchedulePaint() {
   SchedulePaintInRect(gfx::Rect(0, 0, bounds_.width(), bounds_.height()));
 }
 
-void Window::OnPaint(gfx::Canvas* canvas) {
-  delegate_->OnPaint(canvas);
+void Window::OnPaintLayer(gfx::Canvas* canvas) {
+  if (delegate_)
+    delegate_->OnPaint(canvas);
 }
 
 }  // namespace aura