Implement a runtime headless mode for Linux

content/browser/browser_main_loop.cc

Index: content/browser/browser_main_loop.cc
diff --git a/content/browser/browser_main_loop.cc b/content/browser/browser_main_loop.cc
index 86a5d31e2073c47e72ef333a56bdd18084e8d28e..5e6338c73dde73f996ef05f7cef2f8e3865f69a6 100644
--- a/content/browser/browser_main_loop.cc
+++ b/content/browser/browser_main_loop.cc
@@ -99,6 +99,7 @@
 #include "skia/ext/skia_memory_dump_provider.h"
 #include "sql/sql_memory_dump_provider.h"
 #include "ui/base/clipboard/clipboard.h"
+#include "ui/gfx/switches.h"
 
 #if defined(USE_AURA) || defined(OS_MACOSX)
 #include "content/browser/compositor/image_transport_factory.h"
@@ -394,6 +395,8 @@ class GpuDataManagerVisualProxy : public GpuDataManagerObserver {
   }
 
   void OnGpuInfoUpdate() override {
+    if (base::CommandLine::ForCurrentProcess()->HasSwitch(switches::kHeadless))
+      return;
     gpu::GPUInfo gpu_info = gpu_data_manager_->GetGPUInfo();
     if (!ui::XVisualManager::GetInstance()->OnGPUInfoChanged(
             gpu_info.software_rendering ||
@@ -1479,7 +1482,8 @@ bool BrowserMainLoop::InitializeToolkit() {
 #if defined(USE_AURA)
 
 #if defined(USE_X11)
-  if (!gfx::GetXDisplay()) {
+  if (!parsed_command_line_.HasSwitch(switches::kHeadless) &&
+      !gfx::GetXDisplay()) {
     LOG(ERROR) << "Unable to open X display.";
     return false;
   }