disable aero glass for Vista.

ui/base/win/shell.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/base/win/shell.h"
 
 #include <dwmapi.h>
 #include <shlobj.h>  // Must be before propkey.
 #include <propkey.h>
 #include <shellapi.h>
@@ skipping 131 matching lines @@
 bool IsAeroGlassEnabled() {
   // For testing in Win8 (where it is not possible to disable composition) the
   // user can specify this command line switch to mimic the behavior.  In this
   // mode, cross-HWND transparency is not supported and various types of
   // widgets fallback to more simplified rendering behavior.
   if (CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kDisableDwmComposition))
     return false;
 
   base::win::Version version = base::win::GetVersion();
   base::debug::Alias(&version);  // TODO(scottmg): http://crbug.com/431549.

[scottmg, 2014/12/05 22:39:55]

This is unnecessary now, would you mind deleting it?

-  if (version < base::win::VERSION_VISTA)
+  // technically Aero glass works in Vista but we want to put XP and Vista

[scottmg, 2014/12/05 22:39:55]

nit; capital T.

+  // at the same feature level. See bug 426573.
+  if (version < base::win::VERSION_WIN7)
     return false;
   // If composition is not enabled, we behave like on XP.
   BOOL enabled = FALSE;
   return SUCCEEDED(DwmIsCompositionEnabled(&enabled)) && enabled;
 }
 
 }  // namespace win
 }  // namespace ui