Cache a screen compatible DC to avoid re-creating it excessively.

ui/views/widget/native_widget_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/native_widget_win.h"
 
 #include <dwmapi.h>
 #include <shellapi.h>
 
 #include <algorithm>
@@ skipping 1295 matching lines @@
 
 void NativeWidgetWin::OnDestroy() {
   delegate_->OnNativeWidgetDestroying();
   if (drop_target_.get()) {
     RevokeDragDrop(hwnd());
     drop_target_ = NULL;
   }
 }
 
 void NativeWidgetWin::OnDisplayChange(UINT bits_per_pixel, CSize screen_size) {
+  gfx::Screen::ReleaseCompatibleDC();

[sky, 2012/02/03 18:34:06]

This isn't the right place for a release, and it doesn't cover win aura. Instead
create a singleton window that listens for this sort of thing. I want to say we
have such an object some where (ProcessSingleton is a bit similar), but I
couldn't readily locate it.

   GetWidget()->widget_delegate()->OnDisplayChanged();
 }
 
 LRESULT NativeWidgetWin::OnDwmCompositionChanged(UINT msg,
                                                  WPARAM w_param,
                                                  LPARAM l_param) {
   if (!GetWidget()->non_client_view()) {
     SetMsgHandled(FALSE);
     return 0;
   }
@@ skipping 1282 matching lines @@
   return (GetKeyState(VK_LBUTTON) & 0x80) ||
     (GetKeyState(VK_RBUTTON) & 0x80) ||
     (GetKeyState(VK_MBUTTON) & 0x80) ||
     (GetKeyState(VK_XBUTTON1) & 0x80) ||
     (GetKeyState(VK_XBUTTON2) & 0x80);
 }
 
 }  // namespace internal
 
 }  // namespace views