Call xglMakeCurrent for each command buffer to allow for multiple GL contexts...

gpu/command_buffer/service/x_utils.cc

Index: gpu/command_buffer/service/x_utils.cc
===================================================================
--- gpu/command_buffer/service/x_utils.cc	(revision 36557)
+++ gpu/command_buffer/service/x_utils.cc	(working copy)
@@ -74,6 +74,10 @@
 }
 
 bool XWindowWrapper::MakeCurrent() {
+  if (glXGetCurrentDrawable() == window &&
+      glXGetCurrentContext() == context_) {
+    return true;
+  }
   if (glXMakeCurrent(display_, window_, context_) != True) {
     glXDestroyContext(display_, context_);
     context_ = 0;