Switch DRM platform to using a separate thread

ui/ozone/platform/drm/gpu/gbm_surface.cc

Index: ui/ozone/platform/drm/gpu/gbm_surface.cc
diff --git a/ui/ozone/platform/drm/gpu/gbm_surface.cc b/ui/ozone/platform/drm/gpu/gbm_surface.cc
index fcdf5d53a05a89d325336b543d9b96ee8abed39e..321760b4aa6c4c0ad29185c4b6b8d9fed0ad42a8 100644
--- a/ui/ozone/platform/drm/gpu/gbm_surface.cc
+++ b/ui/ozone/platform/drm/gpu/gbm_surface.cc
@@ -9,7 +9,7 @@
 #include "base/bind.h"
 #include "base/logging.h"
 #include "ui/ozone/platform/drm/gpu/drm_buffer.h"
-#include "ui/ozone/platform/drm/gpu/drm_window.h"
+#include "ui/ozone/platform/drm/gpu/drm_window_proxy.h"
 #include "ui/ozone/platform/drm/gpu/gbm_buffer_base.h"
 #include "ui/ozone/platform/drm/gpu/gbm_device.h"
 #include "ui/ozone/platform/drm/gpu/hardware_display_controller.h"
@@ -83,13 +83,13 @@ void GbmSurfaceBuffer::Destroy(gbm_bo* buffer, void* data) {
 
 }  // namespace
 
-GbmSurface::GbmSurface(DrmWindow* window, const scoped_refptr<GbmDevice>& gbm)
-    : GbmSurfaceless(window, NULL),
+GbmSurface::GbmSurface(scoped_ptr<DrmWindowProxy> window,
+                       const scoped_refptr<GbmDevice>& gbm)
+    : GbmSurfaceless(window.Pass()),
       gbm_(gbm),
       native_surface_(NULL),
       current_buffer_(NULL),
-      weak_factory_(this) {
-}
+      weak_factory_(this) {}
 
 GbmSurface::~GbmSurface() {
   if (current_buffer_)
@@ -105,8 +105,8 @@ bool GbmSurface::Initialize() {
   // IPCs arrive), initialize the size to a valid value such that surface
   // creation doesn't fail.
   gfx::Size size(1, 1);
-  if (window_->GetController()) {
-    size = window_->GetController()->GetModeSize();
+  if (!window_->GetBounds().size().IsEmpty()) {
+    size = window_->GetBounds().size();
   }
   // TODO(dnicoara) Check underlying system support for pixel format.
   native_surface_ = gbm_surface_create(