Pass root ServerWindow id to FrameGenerator.

services/ui/ws/display.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 SERVICES_UI_WS_DISPLAY_H_
 #define SERVICES_UI_WS_DISPLAY_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 145 matching lines @@
   // Inits the necessary state once the display is ready.
   void InitWindowManagerDisplayRootsIfNecessary();
 
   // Creates the set of WindowManagerDisplayRoots from the
   // WindowManagerWindowTreeFactorySet.
   void CreateWindowManagerDisplayRootsFromFactories();
 
   void CreateWindowManagerDisplayRootFromFactory(
       WindowManagerWindowTreeFactory* factory);
 
+  // Creates the root ServerWindow for this display. The root window will have
+  // |size| in DIP.

[sky, 2016/10/25 19:23:31]

I thought we were keeping mus itself pixel?

[kylechar, 2016/10/26 14:13:16]

Mus has knowledge of DIP and DPP. The ServerWindow sizes are in DIP though to
match the client window coordinates.

[kylechar, 2016/10/26 14:55:23]

Hmm, it seems like there has been a bit of confusion here. Since I added the
support for device scale factor I've always been creating a ServerWindow with
DIP size. Talking to sadrul@ that doesn't match what is expected. I'll update
this in a separate CL.

+  void CreateRootWindow(const gfx::Size& size);
+
   // PlatformDisplayDelegate:
-  void CreateRootWindow(const gfx::Size& size) override;
   ServerWindow* GetRootWindow() override;
   bool IsInHighContrastMode() override;
   void OnEvent(const ui::Event& event) override;
   void OnNativeCaptureLost() override;
 
   // FocusControllerDelegate:
   bool CanHaveActiveChildren(ServerWindow* window) const override;
 
   // FocusControllerObserver:
   void OnActivationChanged(ServerWindow* old_active_window,
@@ skipping 24 matching lines @@
 
   WindowManagerDisplayRootMap window_manager_display_root_map_;
 
   DISALLOW_COPY_AND_ASSIGN(Display);
 };
 
 }  // namespace ws
 }  // namespace ui
 
 #endif  // SERVICES_UI_WS_DISPLAY_H_