Filter out data urls in the preload scanner

third_party/WebKit/Source/core/html/parser/PreloadRequest.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef PreloadRequest_h
 #define PreloadRequest_h
 
 #include "core/fetch/ClientHintsPreferences.h"
 #include "core/fetch/FetchRequest.h"
 #include "core/fetch/IntegrityMetadata.h"
@@ skipping 12 matching lines @@
 class PreloadRequest {
   USING_FAST_MALLOC(PreloadRequest);
 
  public:
   enum RequestType {
     RequestTypePreload,
     RequestTypePreconnect,
     RequestTypeLinkRelPreload
   };
 
-  static std::unique_ptr<PreloadRequest> create(
+  // TODO(csharrison): Move the implementation to the cpp file when core/html
+  // gets its own testing source set in html/BUILD.gn.
+  static std::unique_ptr<PreloadRequest> createIfNeeded(
       const String& initiatorName,
       const TextPosition& initiatorPosition,
       const String& resourceURL,
       const KURL& baseURL,
       Resource::Type resourceType,
       const ReferrerPolicy referrerPolicy,
       const FetchRequest::ResourceWidth& resourceWidth =
           FetchRequest::ResourceWidth(),
       const ClientHintsPreferences& clientHintsPreferences =
           ClientHintsPreferences(),
       RequestType requestType = RequestTypePreload) {
+    // Never preload data URLs. We also disallow relative ref URLs which become
+    // data URLs if the document's URL is a data URL. We don't want to create
+    // extra resource requests with data URLs to avoid copy / initialization
+    // overhead, which can be significant for large URLs.
+    if (resourceURL.isEmpty() || resourceURL.startsWith("#") ||
+        protocolIs(resourceURL, "data")) {
+      return nullptr;
+    }
     return wrapUnique(new PreloadRequest(
         initiatorName, initiatorPosition, resourceURL, baseURL, resourceType,
         resourceWidth, clientHintsPreferences, requestType, referrerPolicy));
   }
 
   bool isSafeToSendToAnotherThread() const;
 
   FetchRequest resourceRequest(Document*);
 
   const String& charset() const { return m_charset; }
@@ skipping 78 matching lines @@
 
   // Used for deprecation warnings.
   bool m_hasInvalidTypeOrLanguage = false;
 };
 
 typedef Vector<std::unique_ptr<PreloadRequest>> PreloadRequestStream;
 
 }  // namespace blink
 
 #endif