Adds a porting layer so aura can be made to work with mus

ui/aura/window_port.h

+// Copyright 2016 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_AURA_WINDOW_PORT_H_
+#define UI_AURA_WINDOW_PORT_H_
+
+#include <stdint.h>
+
+#include <memory>
+#include <string>
+
+#include "base/observer_list.h"
+#include "base/strings/string16.h"
+#include "ui/aura/aura_export.h"
+
+namespace gfx {
+class Rect;
+}
+
+namespace aura {
+
+class Window;
+class WindowObserver;
+
+// See comments in OnWillChangeProperty() for details.
+struct AURA_EXPORT WindowPortPropertyData {
+  virtual ~WindowPortPropertyData() {}
+};
+
+// See comments in Init() for details.
+struct AURA_EXPORT WindowPortInitData {
+  virtual ~WindowPortInitData() {}
+};
+
+// WindowPort defines an interface to enable Window to be used with or without
+// mus. WindowPort is owned by Window and called at key points in Windows
+// lifetime that enable Window to be used in both environments.
+//
+// If a Window is created without an explicit WindwPort then

[sadrul, 2016/10/26 04:25:55]

*WindowPort

[sky, 2016/10/26 16:25:21]

Done.

+// Env::CreateWindowPort() is used to create the WindowPort.
+class AURA_EXPORT WindowPort {
+ public:
+  virtual ~WindowPort() {}
+
+  // Called from Window::Init(). The return value of this is supplied to
+  // OnInitDone() and is used to allow the WindowPort to pass data between the
+  // two functions.
+  virtual std::unique_ptr<WindowPortInitData> Init(Window* window) = 0;

[sadrul, 2016/10/26 04:25:55]

Alternatively, this could be OnPreInit() and OnPostInit(), and since each
WindowPort services only a single window, it can manage the init-data by itself.

[sky, 2016/10/26 16:25:21]

The reason I created the structure is so that WindowPortMus doesn't need to
track state that is only used during init. That is, WindowPortMus needs
calculate some values that are only needed in PostInit. If I didn't have the
data type that is returned from OnPreInit and fed into OnPostInit then
WindowPortMus would need to keep around data that is only used during init.

I renamed the members.

+
+  virtual void OnInitDone(std::unique_ptr<WindowPortInitData> data) = 0;
+
+  virtual void OnDeviceScaleFactorChanged(float device_scale_factor) = 0;
+
+  // Called when a window is being added as a child. |child| may already have
+  // a parent, but its parent is not the Window this WindowPort is associated
+  // with.
+  virtual void OnWillAddChild(Window* child) = 0;
+
+  virtual void OnWillRemoveChild(Window* child) = 0;
+
+  // Called to move the child at |current_index| to |dest_index|. |dest_index|
+  // is calculated assuming the window at |current_index| has been removed, e.g.
+  //   Window* child = children_[current_index];
+  //   children_.erase(children_.begin() + current_index);
+  //   children_.insert(children_.begin() + dest_index, child);
+  virtual void OnWillMoveChild(size_t current_index, size_t dest_index) = 0;
+
+  virtual void OnVisibilityChanged(bool visible) = 0;
+
+  virtual void OnDidChangeBounds(const gfx::Rect& old_bounds,
+                                 const gfx::Rect& new_bounds) = 0;
+
+  // Called before a property is changed. The return value from this is supplied
+  // into OnPropertyChanged() so that WindowPort may pass data between the two
+  // calls.
+  virtual std::unique_ptr<WindowPortPropertyData> OnWillChangeProperty(
+      const void* key) = 0;
+
+  // Called after a property changes, but before observers are notified. |data|
+  // is the return value from OnWillChangeProperty().
+  virtual void OnPropertyChanged(
+      const void* key,
+      std::unique_ptr<WindowPortPropertyData> data) = 0;

[sadrul, 2016/10/26 04:25:55]

Same comment here re: WindowPortPropertyData.

[sky, 2016/10/26 16:25:21]

Same comment as above. Allowing this to pass around data makes it easy for
windowportmus.

+
+ protected:
+  // Returns the WindowPort associated with a Window.
+  static WindowPort* Get(Window* window);
+
+  // Returns the ObserverList of a Window.
+  static base::ObserverList<WindowObserver, true>* GetObservers(Window* window);
+};
+
+}  // namespace aura
+
+#endif  // UI_AURA_WINDOW_PORT_H_