Prefetch @import files from CSS files.

Source/core/html/HTMLLinkElement.h

Index: Source/core/html/HTMLLinkElement.h
diff --git a/Source/core/html/HTMLLinkElement.h b/Source/core/html/HTMLLinkElement.h
index 10c44725ed30ece5cddf66c89d372bc43e6fc40d..98d286b3cdf42b73876b7e161c50ef6bf49d4c9c 100644
--- a/Source/core/html/HTMLLinkElement.h
+++ b/Source/core/html/HTMLLinkElement.h
@@ -33,8 +33,10 @@
 #include "core/html/HTMLElement.h"
 #include "core/html/LinkRelAttribute.h"
 #include "core/html/LinkResource.h"
+#include "core/html/parser/CSSPreloadScanner.h"
 #include "core/loader/LinkLoader.h"
 #include "core/loader/LinkLoaderClient.h"
+#include "platform/text/SegmentedString.h"
 
 namespace blink {
 
@@ -87,6 +89,7 @@ public:
 private:
     // From StyleSheetResourceClient
     virtual void setCSSStyleSheet(const String& href, const KURL& baseURL, const String& charset, const CSSStyleSheetResource*) OVERRIDE;
+    virtual void dataReceived(const CSSStyleSheetResource* cachedStyleSheet, const char* data, int length) OVERRIDE;
 
     enum DisabledState {
         Unset,
@@ -106,6 +109,8 @@ private:
     Document& document();
 
     RefPtrWillBeMember<CSSStyleSheet> m_sheet;
+    OwnPtr<CSSPreloadScanner> m_preloadScanner;
+    OwnPtr<SegmentedString> m_preloadInput;
     DisabledState m_disabledState;
     PendingSheetType m_pendingSheetType;
     bool m_loading;