Make DocumentResource to be a subclass of TextResource

third_party/WebKit/Source/core/fetch/DocumentResource.h

Index: third_party/WebKit/Source/core/fetch/DocumentResource.h
diff --git a/third_party/WebKit/Source/core/fetch/DocumentResource.h b/third_party/WebKit/Source/core/fetch/DocumentResource.h
index ea70a68179e9fc72c8b21d8deb278432c1e29f2b..73d4d3262a607b597c6b7731e0bc548e5260046f 100644
--- a/third_party/WebKit/Source/core/fetch/DocumentResource.h
+++ b/third_party/WebKit/Source/core/fetch/DocumentResource.h
@@ -25,6 +25,7 @@
 
 #include "core/fetch/Resource.h"
 #include "core/fetch/ResourceClient.h"
+#include "core/fetch/TextResource.h"
 #include "core/html/parser/TextResourceDecoder.h"
 #include "platform/heap/Handle.h"
 #include <memory>
@@ -35,7 +36,7 @@ class Document;
 class FetchRequest;
 class ResourceFetcher;
 
-class CORE_EXPORT DocumentResource final : public Resource {
+class CORE_EXPORT DocumentResource final : public TextResource {
 public:
     using ClientType = ResourceClient;
 
@@ -45,8 +46,6 @@ public:
 
     Document* document() const { return m_document.get(); }
 
-    void setEncoding(const String&) override;
-    String encoding() const override;
     void checkNotify() override;
 
 private:
@@ -66,7 +65,6 @@ private:
     Document* createDocument(const KURL&);
 
     Member<Document> m_document;
-    std::unique_ptr<TextResourceDecoder> m_decoder;
 };
 
 DEFINE_TYPE_CASTS(DocumentResource, Resource, resource, resource->getType() == Resource::SVGDocument, resource.getType() == Resource::SVGDocument);