Initial Fetch integration for Subresource Integrity

Source/core/html/HTMLLinkElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Rob Buis (rwlbuis@gmail.com)
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 492 matching lines @@
     return m_owner->document();
 }
 
 void LinkStyle::setCSSStyleSheet(const String& href, const KURL& baseURL, const String& charset, const CSSStyleSheetResource* cachedStyleSheet)
 {
     if (!m_owner->inDocument()) {
         ASSERT(!m_sheet);
         return;
     }
 
+    // See the comment in ScriptLoader.cpp about why this check is necessary
+    // here. https://crbug.com/500701.
     if (!cachedStyleSheet->errorOccurred() && !SubresourceIntegrity::CheckSubresourceIntegrity(*m_owner, cachedStyleSheet->sheetText(), KURL(baseURL, href), *cachedStyleSheet)) {
         m_loading = false;
         removePendingSheet();
         notifyLoadedSheetAndAllCriticalSubresources(Node::ErrorOccurredLoadingSubresource);
         return;
     }
 
     // Completing the sheet load may cause scripts to execute.
     RefPtrWillBeRawPtr<Node> protector(m_owner.get());
 
@@ skipping 245 matching lines @@
         removePendingSheet();
 }
 
 DEFINE_TRACE(LinkStyle)
 {
     visitor->trace(m_sheet);
     LinkResource::trace(visitor);
 }
 
 } // namespace blink