Generalize layer mirroring for phantom windows

ui/wm/core/window_util.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/wm/core/window_util.h"
 
 #include "ui/aura/window.h"
 #include "ui/compositor/layer.h"
 #include "ui/compositor/layer_tree_owner.h"
 #include "ui/wm/core/transient_window_manager.h"
@@ skipping 19 matching lines @@
         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);
     }
   }
 }
 
+// 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,
+                    wm::LayerDelegateFactory* factory) {
+  for (auto* child : to_mirror->children()) {
+    ui::Layer* mirror = child->Mirror().release();
+    mirror->set_sync_bounds(true);
+    if (factory && child->delegate())
+      mirror->set_delegate(factory->CreateDelegate(mirror, child));
+    parent->Add(mirror);
+    MirrorChildren(child, mirror, factory);
+  }
+}
+
 }  // namespace
 
 namespace wm {
 
 void ActivateWindow(aura::Window* window) {
   DCHECK(window);
   DCHECK(window->GetRootWindow());
   aura::client::GetActivationClient(window->GetRootWindow())->ActivateWindow(
       window);
 }
@@ skipping 43 matching lines @@
   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);
   }
   return old_layer;
 }
 
+std::unique_ptr<ui::LayerTreeOwner> MirrorLayers(
+    ui::LayerOwner* root,
+    LayerDelegateFactory* factory) {
+  std::unique_ptr<ui::LayerTreeOwner> mirror(
+      new ui::LayerTreeOwner(root->layer()->Mirror().release()));

[sky, 2016/10/13 19:21:33]

MakeUnique.
optional: using the release here is awkward. Would be nice if LayerTreeOwner
took a unique_ptr.

[Dominik Laskowski, 2016/10/13 22:19:39]

Done.

+  if (factory) {
+    mirror->root()->set_delegate(
+        factory->CreateDelegate(mirror->root(), root->layer()));
+  }
+  MirrorChildren(root->layer(), mirror->root(), factory);
+  return mirror;
+}
+
 aura::Window* GetTransientParent(aura::Window* window) {
   return const_cast<aura::Window*>(GetTransientParent(
                                  const_cast<const aura::Window*>(window)));
 }
 
 const aura::Window* GetTransientParent(const aura::Window* window) {
   const TransientWindowManager* manager = TransientWindowManager::Get(window);
   return manager ? manager->transient_parent() : NULL;
 }
 
@@ skipping 18 matching lines @@
 bool HasTransientAncestor(const aura::Window* window,
                           const aura::Window* ancestor) {
   const aura::Window* transient_parent = GetTransientParent(window);
   if (transient_parent == ancestor)
     return true;
   return transient_parent ?
       HasTransientAncestor(transient_parent, ancestor) : false;
 }
 
 }  // namespace wm