Add user-agent flag to headless

headless/app/headless_shell.cc

 // Copyright 2016 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 <memory>
 #include <sstream>
 #include <string>
 
 #include "base/base64.h"
 #include "base/base_switches.h"
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/command_line.h"
 #include "base/files/file_path.h"
 #include "base/json/json_writer.h"
 #include "base/location.h"
 #include "base/memory/weak_ptr.h"
 #include "base/numerics/safe_conversions.h"
 #include "base/strings/string_number_conversions.h"
 #include "headless/app/headless_shell.h"
 #include "headless/app/headless_shell_switches.h"
 #include "headless/public/headless_devtools_target.h"
 #include "headless/public/util/deterministic_http_protocol_handler.h"
 #include "net/base/io_buffer.h"
 #include "net/base/ip_address.h"
 #include "net/base/net_errors.h"
+#include "net/http/http_util.h"
 #include "ui/gfx/geometry/size.h"
 
 namespace headless {
 namespace {
 // Address where to listen to incoming DevTools connections.
 const char kDevToolsHttpServerAddress[] = "127.0.0.1";
 // Default file name for screenshot. Can be overriden by "--screenshot" switch.
 const char kDefaultScreenshotFileName[] = "screenshot.png";
 
 bool ParseWindowSize(std::string window_size, gfx::Size* parsed_window_size) {
@@ skipping 475 matching lines @@
       return EXIT_FAILURE;
     }
     builder.SetWindowSize(parsed_window_size);
   }
 
   if (command_line.HasSwitch(switches::kHideScrollbars)) {
     builder.SetOverrideWebPreferencesCallback(base::Bind([](
         WebPreferences* preferences) { preferences->hide_scrollbars = true; }));
   }
 
+  if (command_line.HasSwitch(switches::kUserAgent)) {
+    std::string ua = command_line.GetSwitchValueASCII(switches::kUserAgent);
+    if (net::HttpUtil::IsValidHeaderValue(ua))
+      builder.SetUserAgent(ua);
+  }
+
   return HeadlessBrowserMain(
       builder.Build(),
       base::Bind(&HeadlessShell::OnStart, base::Unretained(&shell)));
 }
 
 }  // namespace headless