Only Call EnableChildWindowDpiMessage When Window Has A Frame

ui/views/win/hwnd_message_handler.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/views/win/hwnd_message_handler.h"
 
 #include <dwmapi.h>
 #include <oleacc.h>
 #include <shellapi.h>
 #include <tchar.h>
@@ skipping 331 matching lines @@
 }
 
 void HWNDMessageHandler::Init(HWND parent, const gfx::Rect& bounds) {
   TRACE_EVENT0("views", "HWNDMessageHandler::Init");
   GetMonitorAndRects(bounds.ToRECT(), &last_monitor_, &last_monitor_rect_,
                      &last_work_area_);
 
   // Create the window.
   WindowImpl::Init(parent, bounds);
 
+  if (delegate_->HasFrame() && base::win::IsProcessPerMonitorDpiAware()) {
+    static auto enable_child_window_dpi_message_func = []() {
+      // Derived signature; not available in headers.
+      // This call gets Windows to scale the non-client area when WM_DPICHANGED
+      // is fired.
+      using EnableChildWindowDpiMessagePtr = LRESULT (WINAPI*)(HWND, BOOL);
+      return reinterpret_cast<EnableChildWindowDpiMessagePtr>(
+                 GetProcAddress(GetModuleHandle(L"user32.dll"),
+                                "EnableChildWindowDpiMessage"));
+    }();
+    if (enable_child_window_dpi_message_func)
+      enable_child_window_dpi_message_func(hwnd(), TRUE);
+  }
+
   prop_window_target_.reset(new ui::ViewProp(hwnd(),
                             ui::WindowEventTarget::kWin32InputEventTarget,
                             static_cast<ui::WindowEventTarget*>(this)));
 
   // Direct Manipulation is enabled on Windows 10+. The CreateInstance function
   // returns NULL if Direct Manipulation is not available.
   direct_manipulation_helper_ =
       gfx::win::DirectManipulationHelper::CreateInstance();
   if (direct_manipulation_helper_)
     direct_manipulation_helper_->Initialize(hwnd());
@@ skipping 2329 matching lines @@
   MONITORINFO monitor_info = {sizeof(monitor_info)};
   GetMonitorInfo(MonitorFromWindow(hwnd(), MONITOR_DEFAULTTOPRIMARY),
                  &monitor_info);
   gfx::Rect shrunk_rect(monitor_info.rcMonitor);
   shrunk_rect.set_height(shrunk_rect.height() - 1);
   background_fullscreen_hack_ = true;
   SetBoundsInternal(shrunk_rect, false);
 }
 
 }  // namespace views