Add extra headers argument so we don't pass headers in the body.

content/browser/download/mhtml_generation_browsertest.cc

 // Copyright (c) 2012 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 <stdint.h>
 #include <memory>
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/files/file_path.h"
@@ skipping 669 matching lines @@
   const char kFakeContentLocation[] =
       "cid:signal-data-62691-645341c4-62b3-478e-a8c5-e0dfccc3ca02@mhtml.blink";
   base::FilePath path(temp_dir_.GetPath());
   path = path.Append(FILE_PATH_LITERAL("test.mht"));
   GURL url(embedded_test_server()->GetURL("/page_with_image.html"));
   MHTMLGenerationParams params(path);
 
   // Place the extra data we need into the web contents user data.
   std::string content_type(kFakeContentType);
   std::string content_location(kFakeContentLocation);
+  std::string extra_headers;
 
   // Get the MHTMLExtraParts
   MHTMLExtraParts* extra_parts =
       MHTMLExtraParts::FromWebContents(shell()->web_contents());
 
   // Add two extra data parts to the MHTML.
-  extra_parts->AddExtraMHTMLPart(content_type, content_location,
+  extra_parts->AddExtraMHTMLPart(content_type, content_location, extra_headers,
                                  kFakeSignalData1);
-  extra_parts->AddExtraMHTMLPart(content_type, content_location,
+  extra_parts->AddExtraMHTMLPart(content_type, content_location, extra_headers,
                                  kFakeSignalData2);
   EXPECT_EQ(extra_parts->size(), 2);
   GenerateMHTML(params, url);
 
   EXPECT_TRUE(has_mhtml_callback_run());
 
   std::string mhtml;
   {
     base::ThreadRestrictions::ScopedAllowIO allow_io_for_content_verification;
     ASSERT_TRUE(base::ReadFileToString(path, &mhtml));
   }
 
   // Make sure that both extra data parts made it into the mhtml.
   EXPECT_THAT(mhtml, HasSubstr(kFakeSignalData1));
   EXPECT_THAT(mhtml, HasSubstr(kFakeSignalData2));
 }
 
 }  // namespace content