Call EnableNonClientDpiScaling

ui/gfx/win/window_impl.cc

 // Copyright (c) 2012 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.
 
 #include "ui/gfx/win/window_impl.h"
 
 #include <list>
 
 #include "base/bind.h"
 #include "base/debug/alias.h"
@@ skipping 274 matching lines @@
                                      LPARAM l_param) {
   if (message == WM_NCCREATE) {
     CREATESTRUCT* cs = reinterpret_cast<CREATESTRUCT*>(l_param);
     WindowImpl* window = reinterpret_cast<WindowImpl*>(cs->lpCreateParams);
     DCHECK(window);
     gfx::SetWindowUserData(hwnd, window);
     window->hwnd_ = hwnd;
     window->got_create_ = true;
     if (hwnd)
       window->got_valid_hwnd_ = true;
-    return TRUE;
   }
 
   WindowImpl* window = reinterpret_cast<WindowImpl*>(GetWindowUserData(hwnd));

[sky, 2016/12/14 02:42:41]

This isn't necessary for the if case, maybe move declaration above if and move
this to else case?

[robliao, 2016/12/14 18:50:19]

While that is true, this seems more readable and GetWindowUserData is pretty
cheap (it's just grabbing a pointer off of the underlying HWND and only for
extra for WM_NCCREATE which is sent only once in an HWND's lifetime).

Happy to change it if you feel strongly about it, but that would mean we would
have to leave window uninitialized before the if-else check:

WindowImpl* window; // Uninitialized
if (message == WM_NCCREATE) {
  ...
  window = reinterpret_cast<>(cs->lpCreateParams)
  ...
} else {
  window = reinterpret_cast<>(GetWindowUserData(hwnd))
}

or check for WM_NCCREATE twice

const WindowImpl* window = (message == WM_NCCREATE) ? (Get WindowImpl from
l_param) : GetWindowUserData(...)
if (message == WM_NCCREATE) {
  SetWindowLongData(hwnd, window);
  ...
}

[sky, 2016/12/14 18:54:24]

I personally think it's clearer overall to not do the lookup twice.
How about setting it to null?

[robliao, 2016/12/14 19:03:18]

Done.

The main reason I don't like setting it to null is we never read (and shouldn't
read) from the value before it is set below.

   if (!window)
     return 0;
 
   return window->OnWndProc(message, w_param, l_param);
 }
 
 ATOM WindowImpl::GetWindowClassAtom() {
   HICON icon = GetDefaultWindowIcon();
   HICON small_icon = GetSmallWindowIcon();
   ClassInfo class_info(initial_class_style(), icon, small_icon);
   return ClassRegistrar::GetInstance()->RetrieveClassAtom(class_info);
 }
 
 }  // namespace gfx