Fix xcb crash when creating gl context

ui/gl/gl_context_glx.cc

Index: ui/gl/gl_context_glx.cc
diff --git a/ui/gl/gl_context_glx.cc b/ui/gl/gl_context_glx.cc
index e5793f4376ef18db5ff11b115858fd7b75f2363f..4be08f647d685a15702562c46a9d101c32dc967d 100644
--- a/ui/gl/gl_context_glx.cc
+++ b/ui/gl/gl_context_glx.cc
@@ -57,6 +57,8 @@ GLXContext CreateContextAttribs(Display* display,
   // When creating a context with glXCreateContextAttribsARB, a variety of X11
   // errors can be generated. To prevent these errors from crashing our process,
   // we simply ignore them and only look if the GLXContext was created.
+  // Sync to ensure any errors generated are processed.
+  XSync(display, False);
   auto old_error_handler = XSetErrorHandler(IgnoreX11Errors);
   GLXContext context =
       glXCreateContextAttribsARB(display, config, share, True, attribs.data());