Preload scan external CSS for @import

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

Index: third_party/WebKit/Source/core/fetch/StyleSheetResourceClient.h
diff --git a/third_party/WebKit/Source/core/fetch/StyleSheetResourceClient.h b/third_party/WebKit/Source/core/fetch/StyleSheetResourceClient.h
index a95d456f46acb7c712e3ee7f5c35ad6619123295..9703e0635c4bbf7dab679b3b8ea63ecc4dca155f 100644
--- a/third_party/WebKit/Source/core/fetch/StyleSheetResourceClient.h
+++ b/third_party/WebKit/Source/core/fetch/StyleSheetResourceClient.h
@@ -41,6 +41,11 @@ public:
     virtual void setCSSStyleSheet(const String& /* href */, const KURL& /* baseURL */, const String& /* charset */, const CSSStyleSheetResource*) {}
     virtual void setXSLStyleSheet(const String& /* href */, const KURL& /* baseURL */, const String& /* sheet */) {}
 
+    // This gets called on the very first appendData call for the
+    // CSSStyleSheetResource. Note this is not called for StyleSheetResources
+    // other than CSSStyleSheetResources.
+    virtual void didAppendFirstData(const CSSStyleSheetResource*) {}
+
     DEFINE_INLINE_VIRTUAL_TRACE() {}
 };