Implement a runtime headless mode for Linux

ui/gl/init/gl_initializer_x11.cc

Index: ui/gl/init/gl_initializer_x11.cc
diff --git a/ui/gl/init/gl_initializer_x11.cc b/ui/gl/init/gl_initializer_x11.cc
index fc8435d3eacec296067896c236bc87c1e2cf9d31..35a84cbc974e6157a0f2f6c654384aafd7f9c470 100644
--- a/ui/gl/init/gl_initializer_x11.cc
+++ b/ui/gl/init/gl_initializer_x11.cc
@@ -9,6 +9,7 @@
 #include "base/path_service.h"
 #include "base/threading/thread_restrictions.h"
 #include "build/build_config.h"
+#include "ui/gfx/switches.h"
 #include "ui/gfx/x/x11_types.h"
 #include "ui/gl/gl_bindings.h"
 #include "ui/gl/gl_egl_api_implementation.h"
@@ -124,6 +125,11 @@ bool InitializeStaticEGLInternal() {
 }  // namespace
 
 bool InitializeGLOneOffPlatform() {
+  const base::CommandLine* command_line =
+      base::CommandLine::ForCurrentProcess();
+  if (command_line->HasSwitch(switches::kHeadless))
+    return true;
+
   switch (GetGLImplementation()) {
     case kGLImplementationDesktopGL:
       if (!GLSurfaceGLX::InitializeOneOff()) {