Generalize layer mirroring for phantom windows

ui/wm/core/window_util.cc

Index: ui/wm/core/window_util.cc
diff --git a/ui/wm/core/window_util.cc b/ui/wm/core/window_util.cc
index 0dc44d50da993b8a289b2f4ce15f04b240662d9c..39fa162969b966ccbbee172c43f5c6cde6b85117 100644
--- a/ui/wm/core/window_util.cc
+++ b/ui/wm/core/window_util.cc
@@ -4,6 +4,7 @@
 
 #include "ui/wm/core/window_util.h"
 
+#include "base/memory/ptr_util.h"
 #include "ui/aura/window.h"
 #include "ui/compositor/layer.h"
 #include "ui/compositor/layer_tree_owner.h"
@@ -16,9 +17,7 @@ namespace {
 // cloned children to |parent|.
 //
 // WARNING: It is assumed that |parent| is ultimately owned by a LayerTreeOwner.
-void CloneChildren(ui::Layer* to_clone,
-                   ui::Layer* parent,
-                   wm::LayerDelegateFactory* factory) {
+void CloneChildren(ui::Layer* to_clone, ui::Layer* parent) {
   typedef std::vector<ui::Layer*> Layers;
   // Make a copy of the children since RecreateLayer() mutates it.
   Layers children(to_clone->children());
@@ -26,17 +25,29 @@ void CloneChildren(ui::Layer* to_clone,
     ui::LayerOwner* owner = (*i)->owner();
     ui::Layer* old_layer = owner ? owner->RecreateLayer().release() : NULL;
     if (old_layer) {
-      if (factory && owner->layer()->delegate())
-        old_layer->set_delegate(
-            factory->CreateDelegate(old_layer, owner->layer()));
       parent->Add(old_layer);
       // RecreateLayer() moves the existing children to the new layer. Create a
       // copy of those.
-      CloneChildren(owner->layer(), old_layer, factory);
+      CloneChildren(owner->layer(), old_layer);
     }
   }
 }
 
+// Invokes Mirror() on all the children of |to_mirror|, adding the newly cloned
+// children to |parent|.
+//
+// WARNING: It is assumed that |parent| is ultimately owned by a LayerTreeOwner.
+void MirrorChildren(ui::Layer* to_mirror,
+                    ui::Layer* parent,
+                    bool sync_bounds) {
+  for (auto* child : to_mirror->children()) {
+    child->set_sync_bounds(sync_bounds);
+    ui::Layer* mirror = child->Mirror().release();
+    parent->Add(mirror);
+    MirrorChildren(child, mirror, sync_bounds);
+  }
+}
+
 }  // namespace
 
 namespace wm {
@@ -85,21 +96,20 @@ aura::Window* GetToplevelWindow(aura::Window* window) {
   return client ? client->GetToplevelWindow(window) : NULL;
 }
 
-std::unique_ptr<ui::LayerTreeOwner> RecreateLayers(
-    ui::LayerOwner* root,
-    LayerDelegateFactory* factory) {
-  std::unique_ptr<ui::LayerTreeOwner> old_layer(
-      new ui::LayerTreeOwner(root->RecreateLayer().release()));
-  if (old_layer->root()) {
-    if (factory) {
-      old_layer->root()->set_delegate(
-          factory->CreateDelegate(old_layer->root(), root->layer()));
-    }
-    CloneChildren(root->layer(), old_layer->root(), factory);
-  }
+std::unique_ptr<ui::LayerTreeOwner> RecreateLayers(ui::LayerOwner* root) {
+  DCHECK(root->OwnsLayer());
+  auto old_layer = base::MakeUnique<ui::LayerTreeOwner>(root->RecreateLayer());
+  CloneChildren(root->layer(), old_layer->root());
   return old_layer;
 }
 
+std::unique_ptr<ui::LayerTreeOwner> MirrorLayers(
+    ui::LayerOwner* root, bool sync_bounds) {
+  auto mirror = base::MakeUnique<ui::LayerTreeOwner>(root->layer()->Mirror());
+  MirrorChildren(root->layer(), mirror->root(), sync_bounds);
+  return mirror;
+}
+
 aura::Window* GetTransientParent(aura::Window* window) {
   return const_cast<aura::Window*>(GetTransientParent(
                                  const_cast<const aura::Window*>(window)));