Do FinishAllRendering in WM_WINDOWPOSCHANGING

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/win/metro.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 889 matching lines @@
                                              WPARAM w_param,
                                              LPARAM l_param) {
 }
 
 bool DesktopWindowTreeHostWin::HandleScrollEvent(
     const ui::ScrollEvent& event) {
   SendEventToProcessor(const_cast<ui::ScrollEvent*>(&event));
   return event.handled();
 }
 
+void DesktopWindowTreeHostWin::HandleWindowSizeChanging() {
+  if (compositor())
+    compositor()->FinishAllRendering();
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // 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