Moves management of transients out of Window

ui/views/corewm/transient_window_manager.h

Index: ui/views/corewm/transient_window_manager.h
diff --git a/ui/views/corewm/transient_window_manager.h b/ui/views/corewm/transient_window_manager.h
new file mode 100644
index 0000000000000000000000000000000000000000..98bb3e06a36a011875c935a44d621600ac45ade8
--- /dev/null
+++ b/ui/views/corewm/transient_window_manager.h
@@ -0,0 +1,96 @@
+// Copyright (c) 2014 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.
+
+#ifndef UI_VIEWS_COREWM_TRANSIENT_WINDOW_MANAGER_H_
+#define UI_VIEWS_COREWM_TRANSIENT_WINDOW_MANAGER_H_
+
+#include <vector>
+
+#include "ui/aura/window_observer.h"
+#include "ui/views/views_export.h"
+
+namespace views {
+namespace corewm {
+
+// TransientWindowManager manages the set of transient children for a window
+// along with the transient parent. Transient children get the following
+// behavior:
+// . The transient parent destroys any transient children when it is
+//   destroyed. This means a transient child is destroyed if either its parent
+//   or transient parent is destroyed.
+// . If a transient child and its transient parent share the same parent, then
+//   transient children are always ordered above the transient parent.
+// Transient windows are typically used for popups and menus.
+// TODO(sky): when we nuke TransientWindowClient rename this to
+// TransientWindowController.
+class VIEWS_EXPORT TransientWindowManager : public aura::WindowObserver {
+ public:
+  typedef std::vector<aura::Window*> Windows;
+
+  virtual ~TransientWindowManager();
+
+  // Returns the TransientWindowManager for |window|. This never returns NULL.
+  static TransientWindowManager* Get(aura::Window* window);
+
+  // Returns the TransientWindowManager for |window| only if it already exists.
+  // WARNING: this may return NULL.
+  static const TransientWindowManager* Get(const aura::Window* window);
+
+  // Adds or removes a transient child.
+  void AddTransientChild(aura::Window* child);
+  void RemoveTransientChild(aura::Window* child);
+
+  const Windows& transient_children() const { return transient_children_; }
+
+  aura::Window* transient_parent() { return transient_parent_; }
+  const aura::Window* transient_parent() const { return transient_parent_; }
+
+  // Returns true if in the process of stacking |child| on top of |target|. That
+  // is, when the stacking order of a window changes (OnWindowStackingChanged())
+  // the transients may get restacked as well. This function can be used to
+  // detect if TransientWindowManager is in the process of stacking a transient
+  // as the result of window stacking changing.
+  bool IsStackingTransient(const aura::Window* child,
+                           const aura::Window* target) const;
+
+ private:
+  // Used to identify when a stacking change needs to restack transients.
+  struct StackingPair {
+    StackingPair(const aura::Window* child, const aura::Window* target)
+        : child(child),
+          target(target) {}
+
+    // The window being moved.
+    const aura::Window* child;
+
+    // |child| is being stacked on top of this.
+    const aura::Window* target;
+  };
+
+  explicit TransientWindowManager(aura::Window* window);
+
+  // Invoked whne |child|'s stacking order changes.
+  void OnChildStackingChanged(aura::Window* child);
+
+  // WindowObserver:
+  virtual void OnWindowVisibilityChanging(aura::Window* window,
+                                          bool visible) OVERRIDE;
+  virtual void OnWindowStackingChanged(aura::Window* window) OVERRIDE;
+  virtual void OnWindowDestroying(aura::Window* window) OVERRIDE;
+
+  aura::Window* window_;
+  aura::Window* transient_parent_;
+  Windows transient_children_;
+
+  // If non-null we're actively restacking transient as the result of a
+  // transient ancestor changing. This is a pointer to a value on the stack.
+  StackingPair* stacking_pair_;
+
+  DISALLOW_COPY_AND_ASSIGN(TransientWindowManager);
+};
+
+}  // namespace corewm
+}  // namespace views
+
+#endif  // UI_VIEWS_COREWM_TRANSIENT_WINDOW_MANAGER_H_