Fix SkXPSDevice

src/device/xps/SkXPSDevice.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef UNICODE
 #define UNICODE
 #endif
@@ skipping 2435 matching lines @@
              CLSID_XpsOMObjectFactory,
              NULL,
              CLSCTX_INPROC_SERVER,
              IID_PPV_ARGS(&this->fXpsFactory)),
          "Could not create factory for layer.");
 
     HRVM(this->fXpsFactory->CreateCanvas(&this->fCurrentXpsCanvas),
          "Could not create canvas for layer.");
 }
 
-bool SkXPSDevice::allowImageFilter(SkImageFilter*) {
+bool SkXPSDevice::allowImageFilter(const SkImageFilter*) {
     return false;
 }