Fix crash in CSSStyleSheetResource::appendData

third_party/WebKit/Source/core/html/parser/CSSPreloadScanner.h

Index: third_party/WebKit/Source/core/html/parser/CSSPreloadScanner.h
diff --git a/third_party/WebKit/Source/core/html/parser/CSSPreloadScanner.h b/third_party/WebKit/Source/core/html/parser/CSSPreloadScanner.h
index 9117b08c3df9761800f35a2520566af23a98033d..1e50426ebe5ae45e89a3af72bb419a4e7cc71e50 100644
--- a/third_party/WebKit/Source/core/html/parser/CSSPreloadScanner.h
+++ b/third_party/WebKit/Source/core/html/parser/CSSPreloadScanner.h
@@ -27,6 +27,8 @@
 #ifndef CSSPreloadScanner_h
 #define CSSPreloadScanner_h
 
+#include "core/fetch/ResourceOwner.h"
+#include "core/fetch/StyleSheetResource.h"
 #include "core/fetch/StyleSheetResourceClient.h"
 #include "core/html/parser/HTMLToken.h"
 #include "core/html/parser/PreloadRequest.h"
@@ -85,16 +87,19 @@ private:
 // Each CSSPreloaderResourceClient keeps track of a single CSS resource, and
 // drives a CSSPreloadScanner as raw data arrives for it. This lets us preload
 // @import tags before parsing.
-class CSSPreloaderResourceClient : public StyleSheetResourceClient {
+class CSSPreloaderResourceClient : public GarbageCollectedFinalized<CSSPreloaderResourceClient>, public ResourceOwner<StyleSheetResource> {
+    USING_GARBAGE_COLLECTED_MIXIN(CSSPreloaderResourceClient);
+
 public:
     CSSPreloaderResourceClient(Resource*, HTMLResourcePreloader*);
     void notifyFinished(Resource*) override;
     void didAppendFirstData(const CSSStyleSheetResource*) override;
     String debugName() const override { return "CSSPreloaderResourceClient"; }
 
+    DECLARE_VIRTUAL_TRACE();
+
 private:
-    Persistent<Resource> m_resource;
-    WeakPersistent<HTMLResourcePreloader> m_preloader;
+    WeakMember<HTMLResourcePreloader> m_preloader;
 };
 
 } // namespace blink