Implement a runtime headless mode for Linux

content/gpu/gpu_main.cc

Index: content/gpu/gpu_main.cc
diff --git a/content/gpu/gpu_main.cc b/content/gpu/gpu_main.cc
index 51c2868899c077360575fbf89cab0518e99bc7a0..1ae774219f190a280ef6a0da92e5a3f0b7ee4dbe 100644
--- a/content/gpu/gpu_main.cc
+++ b/content/gpu/gpu_main.cc
@@ -193,32 +193,39 @@ int GpuMain(const MainFunctionParams& parameters) {
 
   logging::SetLogMessageHandler(GpuProcessLogMessageHandler);
 
+  std::unique_ptr<base::MessageLoop> main_message_loop;
+  if (command_line.HasSwitch(switches::kHeadless)) {
+    main_message_loop.reset(
+        new base::MessageLoop(base::MessageLoop::TYPE_DEFAULT));
+  } else {
 #if defined(OS_WIN)
-  // OK to use default non-UI message loop because all GPU windows run on
-  // dedicated thread.
-  base::MessageLoop main_message_loop(base::MessageLoop::TYPE_DEFAULT);
+    // OK to use default non-UI message loop because all GPU windows run on
+    // dedicated thread.
+    base::MessageLoop main_message_loop(base::MessageLoop::TYPE_DEFAULT);

[Eric Seckler, 2016/11/28 15:51:48]

think this won't compile, needs to do main_message_loop.reset() as well

[Sami, 2016/11/28 18:00:36]

Hmm yeah, I think I messed this up while rebasing. Thanks.

 #elif defined(USE_X11)
-  // We need a UI loop so that we can grab the Expose events. See GLSurfaceGLX
-  // and https://crbug.com/326995.
-  base::MessageLoop main_message_loop(base::MessageLoop::TYPE_UI);
-  std::unique_ptr<ui::PlatformEventSource> event_source =
-      ui::PlatformEventSource::CreateDefault();
+    // We need a UI loop so that we can grab the Expose events. See GLSurfaceGLX
+    // and https://crbug.com/326995.
+    main_message_loop.reset(new base::MessageLoop(base::MessageLoop::TYPE_UI));
+    std::unique_ptr<ui::PlatformEventSource> event_source =
+        ui::PlatformEventSource::CreateDefault();
 #elif defined(USE_OZONE) && defined(OZONE_X11)
-  // If we might be running Ozone X11 we need a UI loop to grab Expose events.
-  // See GLSurfaceGLX and https://crbug.com/326995.
-  base::MessageLoop main_message_loop(base::MessageLoop::TYPE_UI);
+    // If we might be running Ozone X11 we need a UI loop to grab Expose events.
+    // See GLSurfaceGLX and https://crbug.com/326995.
+    main_message_loop.reset(new base::MessageLoop(base::MessageLoop::TYPE_UI));
 #elif defined(USE_OZONE)
-  base::MessageLoop main_message_loop(base::MessageLoop::TYPE_DEFAULT);
+    main_message_loop.reset(
+        new base::MessageLoop(base::MessageLoop::TYPE_DEFAULT));
 #elif defined(OS_LINUX)
 #error "Unsupported Linux platform."
 #elif defined(OS_MACOSX)
-  // This is necessary for CoreAnimation layers hosted in the GPU process to be
-  // drawn. See http://crbug.com/312462.
-  std::unique_ptr<base::MessagePump> pump(new base::MessagePumpCFRunLoop());
-  base::MessageLoop main_message_loop(std::move(pump));
+    // This is necessary for CoreAnimation layers hosted in the GPU process to
+    // be drawn. See http://crbug.com/312462.
+    std::unique_ptr<base::MessagePump> pump(new base::MessagePumpCFRunLoop());
+    main_message_loop.reset(new base::MessageLoop(std::move(pump)));
 #else
-  base::MessageLoop main_message_loop(base::MessageLoop::TYPE_IO);
+    main_message_loop.reset(new base::MessageLoop(base::MessageLoop::TYPE_IO));
 #endif
+  }
 
   base::PlatformThread::SetName("CrGpuMain");