PlzNavigate: Add first version of NavigationURLLoader.

content/browser/loader/upload_data_stream_builder.cc

 // Copyright 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/browser/loader/upload_data_stream_builder.h"
 
 #include "base/logging.h"
 #include "content/browser/fileapi/upload_file_system_file_element_reader.h"
 #include "content/common/resource_request_body.h"
 #include "net/base/elements_upload_data_stream.h"
@@ skipping 97 matching lines @@
     const ResourceRequestBody::Element& element = *resolved_elements[i];
     switch (element.type()) {
       case ResourceRequestBody::Element::TYPE_BYTES:
         element_readers.push_back(new BytesElementReader(body, element));
         break;
       case ResourceRequestBody::Element::TYPE_FILE:
         element_readers.push_back(
             new FileElementReader(body, file_task_runner, element));
         break;
       case ResourceRequestBody::Element::TYPE_FILE_FILESYSTEM:
+        // If |body| contains any filesystem URLs, the caller should have
+        // supplied a FileSystemContext.
+        DCHECK(file_system_context);
         element_readers.push_back(
             new content::UploadFileSystemFileElementReader(
                 file_system_context,
                 element.filesystem_url(),
                 element.offset(),
                 element.length(),
                 element.expected_modification_time()));
         break;
       case ResourceRequestBody::Element::TYPE_BLOB:
         // Blob elements should be resolved beforehand.
         NOTREACHED();
         break;
       case ResourceRequestBody::Element::TYPE_UNKNOWN:
         NOTREACHED();
         break;
     }
   }
 
   return make_scoped_ptr(
       new net::ElementsUploadDataStream(element_readers.Pass(),
                                         body->identifier()));
 }
 
 }  // namespace content