Makes it possible for clients to directly create WindowTreeHostMus

ui/aura/window_port.h

Index: ui/aura/window_port.h
diff --git a/ui/aura/window_port.h b/ui/aura/window_port.h
index 6f04399d391424f061297e26dfcd28cad0a6928b..b82305d2206d07bb9c13d90de7e01b41552fede0 100644
--- a/ui/aura/window_port.h
+++ b/ui/aura/window_port.h
@@ -28,11 +28,6 @@ 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.
@@ -43,12 +38,8 @@ 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> OnPreInit(Window* window) = 0;
-
-  virtual void OnPostInit(std::unique_ptr<WindowPortInitData> data) = 0;
+  // Called from Window::Init().
+  virtual void OnPreInit(Window* window) = 0;
 
   virtual void OnDeviceScaleFactorChanged(float device_scale_factor) = 0;