Enable SRI only for same origin and CORS content.

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 491 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;
     }
 
-    if (!SubresourceIntegrity::CheckSubresourceIntegrity(*m_owner, cachedStyleSheet->sheetText(), KURL(KURL(), href), cachedStyleSheet->mimeType())) {
-        m_loading = false;
-        removePendingSheet();
-        notifyLoadedSheetAndAllCriticalSubresources(true);
-        return;
+    if (cachedStyleSheet->isCORSNeededAndFailed() && m_owner->fastHasAttribute(HTMLNames::integrityAttr)) {
+        document().addConsoleMessage(ConsoleMessage::create(SecurityMessageSource, ErrorMessageLevel, "Cannot enforce integrity on non-CORS enabled resource."));

[Mike West, 2015/02/26 08:44:53]

Same question as I had with script: should we just allow the request? I don't
think that's actually what the spec says (e.g.
https://w3c.github.io/webappsec/specs/subresourceintegrity/#is-resource-eligi...
returns false, so
https://w3c.github.io/webappsec/specs/subresourceintegrity/#does-resource-mat...
returns false in step 2.

[jww, 2015/03/06 02:16:42]

Agreed as per my response in ScriptLoader.cpp. Fixed.

+    } else {
+        if (!SubresourceIntegrity::CheckSubresourceIntegrity(*m_owner, cachedStyleSheet->sheetText(), KURL(KURL(), href), cachedStyleSheet->mimeType())) {
+            m_loading = false;
+            removePendingSheet();
+            notifyLoadedSheetAndAllCriticalSubresources(true);
+            return;
+        }
     }
 
     // Completing the sheet load may cause scripts to execute.
     RefPtrWillBeRawPtr<Node> protector(m_owner.get());
 
     CSSParserContext parserContext(m_owner->document(), 0, baseURL, charset);
 
     if (RefPtrWillBeRawPtr<StyleSheetContents> restoredSheet = const_cast<CSSStyleSheetResource*>(cachedStyleSheet)->restoreParsedStyleSheet(parserContext)) {
         ASSERT(restoredSheet->isCacheable());
         ASSERT(!restoredSheet->isLoading());
@@ skipping 225 matching lines @@
         removePendingSheet();
 }
 
 DEFINE_TRACE(LinkStyle)
 {
     visitor->trace(m_sheet);
     LinkResource::trace(visitor);
 }
 
 } // namespace blink