Preload scan external CSS for @import

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

Index: third_party/WebKit/Source/core/fetch/CSSStyleSheetResource.h
diff --git a/third_party/WebKit/Source/core/fetch/CSSStyleSheetResource.h b/third_party/WebKit/Source/core/fetch/CSSStyleSheetResource.h
index 6d3e0acbd8c9dc2bc953174ee3a130d86d9901f6..4ed088e168e0f627cb69711c269486d40a0ba581 100644
--- a/third_party/WebKit/Source/core/fetch/CSSStyleSheetResource.h
+++ b/third_party/WebKit/Source/core/fetch/CSSStyleSheetResource.h
@@ -55,6 +55,8 @@ public:
     StyleSheetContents* restoreParsedStyleSheet(const CSSParserContext&);
     void saveParsedStyleSheet(StyleSheetContents*);
 
+    void appendData(const char* data, size_t length) override;
+
 protected:
     bool isSafeToUnlock() const override;
     void destroyDecodedDataIfPossible() override;
@@ -81,6 +83,8 @@ private:
     String m_decodedSheetText;
 
     Member<StyleSheetContents> m_parsedStyleSheetCache;
+
+    bool m_didNotifyFirstData;
 };
 
 DEFINE_RESOURCE_TYPE_CASTS(CSSStyleSheet);