Introduce AsyncDocumentSubresourceFilter.

third_party/WebKit/public/platform/WebDocumentSubresourceFilter.h

 // 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.
 
 #ifndef WebDocumentSubresourceFilter_h
 #define WebDocumentSubresourceFilter_h
 
+#include "public/platform/WebDocumentSubresourceFilterLoadPolicy.h"
 #include "public/platform/WebURLRequest.h"
 
 namespace blink {
 
 class WebURL;
 
 class WebDocumentSubresourceFilter {
  public:
-  enum LoadPolicy { Allow, Disallow, WouldDisallow };
   virtual ~WebDocumentSubresourceFilter() {}
-  virtual LoadPolicy getLoadPolicy(const WebURL& resourceUrl,
-                                   WebURLRequest::RequestContext) = 0;
+
+  virtual WebDocumentSubresourceFilterLoadPolicy getLoadPolicy(
+      const WebURL& resourceUrl,
+      WebURLRequest::RequestContext) = 0;
 
   // Report that a resource loaded by the document (not a preload) was
   // disallowed.
   virtual void reportDisallowedLoad() = 0;
 };
 
 }  // namespace blink
 
 #endif  // WebDocumentSubresourceFilter_h