add print to pdf for headless

headless/app/headless_shell_switches.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 "headless/app/headless_shell_switches.h"
 
 namespace headless {
 namespace switches {
 
 // The directory breakpad should store minidumps in.
 const char kCrashDumpsDir[] = "crash-dumps-dir";
 
 // Instructs headless_shell to cause network fetches to complete in order of
 // creation. This removes a significant source of network related
 // non-determinism at the cost of slower page loads.
 const char kDeterministicFetch[] = "deterministic-fetch";
 
 // Instructs headless_shell to print document.body.innerHTML to stdout.
 const char kDumpDom[] = "dump-dom";
 
 // Hide scrollbars from screenshots.
 const char kHideScrollbars[] = "hide-scrollbars";
 
+// Save a pdf file of the loaded page.
+const char kPrintToPDF[] = "print-to-pdf";
+
 // Uses a specified proxy server, overrides system settings. This switch only
 // affects HTTP and HTTPS requests.
 const char kProxyServer[] = "proxy-server";
 
 // Use the given address instead of the default loopback for accepting remote
 // debugging connections. Should be used together with --remote-debugging-port.
 // Note that the remote debugging protocol does not perform any authentication,
 // so exposing it too widely can be a security risk.
 const char kRemoteDebuggingAddress[] = "remote-debugging-address";
 
@@ skipping 21 matching lines @@
 // network fetches have completed, timers fire and if the system runs out of
 // virtual time is fastforwarded so the next timer fires immediatley, until the
 // specified virtual time budget is exhausted.
 const char kVirtualTimeBudget[] = "virtual-time-budget";
 
 // Sets the initial window size. Provided as string in the format "800,600".
 const char kWindowSize[] = "window-size";
 
 }  // namespace switches
 }  // namespace headless