Add Plumbing for WM_DPICHANGED

ui/views/widget/desktop_aura/desktop_window_tree_host_win.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/widget/desktop_aura/desktop_window_tree_host_win.h"
 
 #include "base/memory/ptr_util.h"
 #include "third_party/skia/include/core/SkPath.h"
 #include "third_party/skia/include/core/SkRegion.h"
 #include "ui/aura/client/aura_constants.h"
@@ skipping 922 matching lines @@
   // changed (can occur on Windows 10 when snapping a window to the side of
   // the screen). In that case do a resize to the current size to reenable
   // swaps.
   if (compositor()) {
     compositor()->SetScaleAndSize(
         compositor()->device_scale_factor(),
         message_handler_->GetClientAreaBounds().size());
   }
 }
 
+void DesktopWindowTreeHostWin::HandleWindowScaleFactorChanged(
+    float window_scale_factor) {
+  if (compositor()) {
+    compositor()->SetScaleAndSize(
+        window_scale_factor,
+        message_handler_->GetClientAreaBounds().size());
+  }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // DesktopWindowTreeHostWin, private:
 
 Widget* DesktopWindowTreeHostWin::GetWidget() {
   return native_widget_delegate_->AsWidget();
 }
 
 const Widget* DesktopWindowTreeHostWin::GetWidget() const {
   return native_widget_delegate_->AsWidget();
 }
@@ skipping 31 matching lines @@
 
 // static
 DesktopWindowTreeHost* DesktopWindowTreeHost::Create(
     internal::NativeWidgetDelegate* native_widget_delegate,
     DesktopNativeWidgetAura* desktop_native_widget_aura) {
   return new DesktopWindowTreeHostWin(native_widget_delegate,
                                       desktop_native_widget_aura);
 }
 
 }  // namespace views