Use Ash's ShelfWindowWatcher for app panel windows.

ash/common/shelf/shelf_window_watcher_item_delegate.cc

 // Copyright 2013 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 "ash/common/shelf/shelf_window_watcher_item_delegate.h"
 
+#include "ash/common/shelf/shelf_controller.h"
+#include "ash/common/shelf/shelf_model.h"
+#include "ash/common/wm/window_state.h"
+#include "ash/common/wm_lookup.h"
+#include "ash/common/wm_shell.h"
 #include "ash/common/wm_window.h"
 #include "ui/events/event.h"
+#include "ui/views/view.h"
+#include "ui/views/widget/widget.h"
 
 namespace ash {
 
-ShelfWindowWatcherItemDelegate::ShelfWindowWatcherItemDelegate(WmWindow* window)
-    : window_(window) {}
+namespace {
+
+ShelfItemType GetShelfItemType(ShelfID id) {
+  ShelfModel* model = WmShell::Get()->shelf_controller()->model();
+  ShelfItems::const_iterator item = model->ItemByID(id);
+  return item == model->items().end() ? TYPE_UNDEFINED : item->type;
+}
+
+// Moves |window| to the display where |event| occurred; returns true if moved.
+// Note: This was forked from ash/wm/window_util.h's wm::MoveWindowToEventRoot.
+// TODO(msw): Reduce function copies once aura-as-a-mus-client is resolved.
+bool MoveWindowToEventRoot(WmWindow* window, const ui::Event& event) {

[James Cook, 2016/11/02 17:53:44]

I think there's another copy of this in TestShelfItemDelegate. I'm OK with one
forked copy for mustash, but not two. Can you refactor this to share the code?
Maybe just make it a public static method?

[msw, 2016/11/10 21:07:46]

Done (moved to WmWindow in a prior CL).

+  views::View* target = static_cast<views::View*>(event.target());
+  if (!target)
+    return false;
+  WmWindow* target_root =
+      WmLookup::Get()->GetWindowForWidget(target->GetWidget())->GetRootWindow();
+  if (!target_root || target_root == window->GetRootWindow())
+    return false;
+  WmWindow* window_container = target_root->GetChildByShellWindowId(
+      window->GetParent()->GetShellWindowId());
+  window_container->AddChild(window);
+  return true;
+}
+
+}  // namespace
+
+ShelfWindowWatcherItemDelegate::ShelfWindowWatcherItemDelegate(ShelfID id,
+                                                               WmWindow* window)
+    : id_(id), window_(window) {}
 
 ShelfWindowWatcherItemDelegate::~ShelfWindowWatcherItemDelegate() {}
 
 ShelfItemDelegate::PerformedAction ShelfWindowWatcherItemDelegate::ItemSelected(
     const ui::Event& event) {
+  // Move panels attached on another display to the current display.
+  if (GetShelfItemType(id_) == TYPE_APP_PANEL &&
+      window_->GetWindowState()->panel_attached() &&
+      MoveWindowToEventRoot(window_, event)) {
+    window_->Activate();
+    return kExistingWindowActivated;
+  }
+
   if (window_->IsActive()) {
     if (event.type() & ui::ET_KEY_RELEASED) {
       window_->Animate(::wm::WINDOW_ANIMATION_TYPE_BOUNCE);
       return kNoAction;
     }
     window_->Minimize();
     return kExistingWindowMinimized;
   }
   window_->Activate();
   return kExistingWindowActivated;
 }
 
 base::string16 ShelfWindowWatcherItemDelegate::GetTitle() {
   return window_->GetTitle();
 }
 
 ShelfMenuModel* ShelfWindowWatcherItemDelegate::CreateApplicationMenu(
     int event_flags) {
   return nullptr;
 }
 
 bool ShelfWindowWatcherItemDelegate::IsDraggable() {
   return true;
 }
 
 bool ShelfWindowWatcherItemDelegate::CanPin() const {
+  return GetShelfItemType(id_) != TYPE_APP_PANEL;
+}
+
+bool ShelfWindowWatcherItemDelegate::ShouldShowTooltip() {
+  // Do not show tooltips for visible attached app panel windows.
+  return GetShelfItemType(id_) != TYPE_APP_PANEL || !window_->IsVisible() ||
+         !window_->GetWindowState()->panel_attached();
+}
+
+bool ShelfWindowWatcherItemDelegate::IsOpen() const {
   return true;
 }
 
-bool ShelfWindowWatcherItemDelegate::ShouldShowTooltip() {
-  return true;
-}
-
 void ShelfWindowWatcherItemDelegate::Close() {
   window_->CloseWidget();
 }
 
 }  // namespace ash