Avoid cross-origin iframe issues when loading PDF in print preview

content/public/browser/url_data_source.cc

 // Copyright (c) 2013 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.
 
 #include "content/public/browser/url_data_source.h"
 
 #include "content/browser/webui/url_data_manager.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/common/url_constants.h"
 #include "net/url_request/url_request.h"
@@ skipping 43 matching lines @@
 
 bool URLDataSource::ShouldServeMimeTypeAsContentTypeHeader() const {
   return false;
 }
 
 std::string URLDataSource::GetAccessControlAllowOriginForOrigin(
     const std::string& origin) const {
   return std::string();
 }
 
+void URLDataSource::WillServiceRequest(
+      const net::URLRequest* request,
+      std::string* path) const {
+  // In the normal case we want to remove any query strings from the path. This
+  // may not be true for subclasses which can override this behavior.
+  *path = path->substr(0, path->find_last_of('?'));

[Charlie Reis, 2015/07/20 16:49:09]

I don't think this is a good change to make.  Things in content/public should
mainly be interfaces, and the other implementations in this file are small and
don't have side effects.  This code makes a meaningful change to the path in a
way that isn't obvious, and it's easy to accidentally prevent this change
(without realizing it) by overriding the method.

+}
+
 }  // namespace content