Enables passing initial properties to top level window creation

ui/aura/window_tree_host_platform.h

 // Copyright 2015 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_TREE_HOST_PLATFORM_H_
 #define UI_AURA_WINDOW_TREE_HOST_PLATFORM_H_
 
 #include <memory>
 
 #include "base/compiler_specific.h"
@@ skipping 25 matching lines @@
   gfx::Rect GetBounds() const override;
   void SetBounds(const gfx::Rect& bounds) override;
   gfx::Point GetLocationOnNativeScreen() const override;
   void SetCapture() override;
   void ReleaseCapture() override;
   void SetCursorNative(gfx::NativeCursor cursor) override;
   void MoveCursorToNative(const gfx::Point& location) override;
   void OnCursorVisibilityChangedNative(bool show) override;
 
  protected:
+  // NOTE: neither of these calls CreateCompositor(); subclasses must call
+  // CreateCompositor() at the appropriate time.

[sadrul, 2016/11/16 18:02:08]

Is this change because the creation of the compositor depends on some of the
attributes on the mus window?

[sky, 2016/11/16 18:45:49]

CreateCompositor() calls window->Init(). window->Init(), for aura-mus, is the
time at which the the window server is asked to create the window. When the
server window is created properties may be provided to help influence initial
configuration of the serverwindow. By delaying the call to CreateCompositor
WindowTreeHostMus now has the ability to set properties on the aura::Window
before Init() is called so that initial properties make there way to
ServerWindow.

   WindowTreeHostPlatform();
   explicit WindowTreeHostPlatform(std::unique_ptr<WindowPort> window_port);
 
   void SetPlatformWindow(std::unique_ptr<ui::PlatformWindow> window);
   ui::PlatformWindow* platform_window() { return window_.get(); }
 
   // ui::PlatformWindowDelegate:
   void OnBoundsChanged(const gfx::Rect& new_bounds) override;
   void OnDamageRect(const gfx::Rect& damaged_region) override;
   void DispatchEvent(ui::Event* event) override;
@@ skipping 11 matching lines @@
   std::unique_ptr<ui::PlatformWindow> window_;
   gfx::NativeCursor current_cursor_;
   gfx::Rect bounds_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowTreeHostPlatform);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_WINDOW_TREE_HOST_PLATFORM_H_