Check the mime type of cross-origin CSS fetched via the Service Worker.

third_party/WebKit/Source/core/css/StyleSheetContents.cpp

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2006, 2007, 2012 Apple 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
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 304 matching lines @@
 const AtomicString& StyleSheetContents::namespaceURIFromPrefix(const AtomicString& prefix)
 {
     return m_namespaces.get(prefix);
 }
 
 void StyleSheetContents::parseAuthorStyleSheet(const CSSStyleSheetResource* cachedStyleSheet, const SecurityOrigin* securityOrigin)
 {
     TRACE_EVENT1("blink,devtools.timeline", "ParseAuthorStyleSheet", "data", InspectorParseAuthorStyleSheetEvent::data(cachedStyleSheet));
 
     bool isSameOriginRequest = securityOrigin && securityOrigin->canRequest(baseURL());
+
+    // When the response was fetched via the Service Worker, the original URL may not be same as the base URL.
+    // FIXME: When we will use the original URL as the base URL, we can remove this check. crbug.com/553535

[Mike West, 2016/04/06 06:54:16]

Nit: s/FIXME/TODO(horo)/

[horo, 2016/04/06 08:13:50]

Done.

+    if (cachedStyleSheet->response().wasFetchedViaServiceWorker() && !securityOrigin->canRequest(cachedStyleSheet->response().originalURLViaServiceWorker()))

[Mike West, 2016/04/06 06:54:16]

What do we do for purely synthetic responses? It seems like those ought to be
considered same-origin.

[horo, 2016/04/06 08:13:50]

Done.
Added isEmpty() checking.

+        isSameOriginRequest = false;
+
     CSSStyleSheetResource::MIMETypeCheck mimeTypeCheck = isQuirksModeBehavior(m_parserContext.mode()) && isSameOriginRequest ? CSSStyleSheetResource::MIMETypeCheck::Lax : CSSStyleSheetResource::MIMETypeCheck::Strict;
     String sheetText = cachedStyleSheet->sheetText(mimeTypeCheck);
 
     const ResourceResponse& response = cachedStyleSheet->response();
     m_sourceMapURL = response.httpHeaderField(HTTPNames::SourceMap);
     if (m_sourceMapURL.isEmpty()) {
         // Try to get deprecated header.
         m_sourceMapURL = response.httpHeaderField(HTTPNames::X_SourceMap);
     }
 
@@ skipping 330 matching lines @@
     visitor->trace(m_ownerRule);
     visitor->trace(m_importRules);
     visitor->trace(m_namespaceRules);
     visitor->trace(m_childRules);
     visitor->trace(m_loadingClients);
     visitor->trace(m_completedClients);
     visitor->trace(m_ruleSet);
 }
 
 } // namespace blink