Implement a runtime headless mode for Linux

content/public/common/content_switches.cc

Index: content/public/common/content_switches.cc
diff --git a/content/public/common/content_switches.cc b/content/public/common/content_switches.cc
index 1668c5a7816c9fd57bad58df9277e38d3a04fefc..9fb4f4a465101d7e9e9880e8cf8e5a7382a85db5 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -576,6 +576,10 @@ const char kGpuStartupDialog[]              = "gpu-startup-dialog";
 // Ignores certificate-related errors.
 const char kIgnoreCertificateErrors[]       = "ignore-certificate-errors";
 
+// Start the browser in headless mode (i.e., without a UI or display server
+// dependencies). Also see remote-debugging-port.
+const char kHeadless[] = "headless";
+
 // Don't allow content to arbitrarily append to the back/forward list.
 // The page must prcoess a user gesture before an entry can be added.
 const char kHistoryEntryRequiresUserGesture[] =