Reland of Add --headless flag to Windows

headless/app/headless_shell.h

 // Copyright 2017 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 HEADLESS_APP_HEADLESS_SHELL_H_
 #define HEADLESS_APP_HEADLESS_SHELL_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 68 matching lines @@
 
   void OnPDFCreated(std::unique_ptr<page::PrintToPDFResult> result);
 
   void WriteFile(const std::string& switch_string,
                  const std::string& default_file_name,
                  const std::string& data);
   void OnFileOpened(const std::string& data,
                     const base::FilePath file_name,
                     base::File::Error error_code);
   void OnFileWritten(const base::FilePath file_name,
-                     const int length,
+                     const size_t length,
                      base::File::Error error_code,
                      int write_result);
   void OnFileClosed(base::File::Error error_code);
 
   bool RemoteDebuggingEnabled() const;
 
   GURL url_;
   HeadlessBrowser* browser_;  // Not owned.
   std::unique_ptr<HeadlessDevToolsClient> devtools_client_;
   HeadlessWebContents* web_contents_;
   bool processed_page_ready_;
   std::unique_ptr<base::FileProxy> file_proxy_;
   HeadlessBrowserContext* browser_context_;
   std::unique_ptr<DeterministicDispatcher> deterministic_dispatcher_;
   base::WeakPtrFactory<HeadlessShell> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(HeadlessShell);
 };
 
 }  // namespace headless
 
 #endif  // HEADLESS_APP_HEADLESS_SHELL_H_