Break StyleImage dependency on LayoutObject

third_party/WebKit/Source/core/css/CSSPaintImageGenerator.cpp

 // Copyright 2016 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 "core/css/CSSPaintImageGenerator.h"
 
 namespace blink {
 
 namespace {
 
 CSSPaintImageGenerator::CSSPaintImageGeneratorCreateFunction g_create_function =
     nullptr;
 
 }  // namespace
 
 // static
 void CSSPaintImageGenerator::Init(
     CSSPaintImageGeneratorCreateFunction create_function) {
   DCHECK(!g_create_function);
   g_create_function = create_function;
 }
 
 // static
 CSSPaintImageGenerator* CSSPaintImageGenerator::Create(const String& name,
-                                                       Document& document,
+                                                       const Document& document,
                                                        Observer* observer) {
   DCHECK(g_create_function);
   return g_create_function(name, document, observer);
 }
 
 CSSPaintImageGenerator::~CSSPaintImageGenerator() {}
 
 }  // namespace blink