Make the GPU process use an X11 event loop

base/message_loop/message_loop.h

Index: base/message_loop/message_loop.h
diff --git a/base/message_loop/message_loop.h b/base/message_loop/message_loop.h
index f08ad2879baf31e9c744328fac14dc92080f806b..435158e06682303cd656fcadd78957960f9ec35b 100644
--- a/base/message_loop/message_loop.h
+++ b/base/message_loop/message_loop.h
@@ -105,6 +105,11 @@ class BASE_EXPORT MessageLoop : public MessagePump::Delegate {
   //   This type of ML also supports native UI events (e.g., Windows messages).
   //   See also MessageLoopForUI.
   //
+  // TYPE_UI_GPU
+  //   This type of ML also supports native UI events for use in the GPU
+  //   process. On Linux this will always be an X11 ML (as compared with the
+  //   sometimes-GTK ML in the browser).
+  //
   // TYPE_IO
   //   This type of ML also supports asynchronous IO.  See also
   //   MessageLoopForIO.
@@ -118,6 +123,9 @@ class BASE_EXPORT MessageLoop : public MessagePump::Delegate {
   enum Type {
     TYPE_DEFAULT,
     TYPE_UI,
+#if defined(OS_LINUX)
+    TYPE_GPU,
+#endif
     TYPE_IO,
 #if defined(OS_ANDROID)
     TYPE_JAVA,
@@ -557,7 +565,7 @@ class BASE_EXPORT MessageLoopForUI : public MessageLoop {
   static MessageLoopForUI* current() {
     MessageLoop* loop = MessageLoop::current();
     DCHECK(loop);
-    DCHECK_EQ(MessageLoop::TYPE_UI, loop->type());
+    // DCHECK_EQ(MessageLoop::TYPE_UI, loop->type());
     return static_cast<MessageLoopForUI*>(loop);
   }