Implement a runtime headless mode for Linux

content/browser/zygote_host/zygote_communication_linux.cc

 // Copyright 2015 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/zygote_host/zygote_communication_linux.h"
 
 #include <string.h>
 #include <sys/socket.h>
 
 #include "base/base_switches.h"
@@ skipping 231 matching lines @@
       *base::CommandLine::ForCurrentProcess();
   if (browser_command_line.HasSwitch(switches::kZygoteCmdPrefix)) {
     cmd_line.PrependWrapper(
         browser_command_line.GetSwitchValueNative(switches::kZygoteCmdPrefix));
   }
   // Append any switches from the browser process that need to be forwarded on
   // to the zygote/renderers.
   // Should this list be obtained from browser_render_process_host.cc?
   static const char* const kForwardSwitches[] = {
       switches::kAllowSandboxDebugging, switches::kAndroidFontsPath,
-      switches::kDisableSeccompFilterSandbox,
-      switches::kEnableHeapProfiling,
+      switches::kDisableSeccompFilterSandbox, switches::kEnableHeapProfiling,
       switches::kEnableLogging,  // Support, e.g., --enable-logging=stderr.
+      switches::kHeadless,
       // Zygote process needs to know what resources to have loaded when it
       // becomes a renderer process.
       switches::kForceDeviceScaleFactor, switches::kLoggingLevel,
       switches::kNoSandbox, switches::kPpapiInProcess,
       switches::kRegisterPepperPlugins, switches::kV, switches::kVModule,
   };
   cmd_line.CopySwitchesFrom(browser_command_line, kForwardSwitches,
                             arraysize(kForwardSwitches));
 
   GetContentClient()->browser()->AppendExtraCommandLineSwitches(&cmd_line, -1);
@@ skipping 63 matching lines @@
   }
   if (ReadSandboxStatus() == -1) {
     return 0;
   }
   have_read_sandbox_status_word_ = true;
   UMA_HISTOGRAM_SPARSE_SLOWLY("Linux.SandboxStatus", sandbox_status_);
   return sandbox_status_;
 }
 
 }  // namespace content