Switch all contexts in a share group to be on the same screen as the window they present to.

content/common/gpu/image_transport_surface_mac.cc

Index: content/common/gpu/image_transport_surface_mac.cc
diff --git a/content/common/gpu/image_transport_surface_mac.cc b/content/common/gpu/image_transport_surface_mac.cc
index 2bb57945aaac684a145c302239bc114a0ffcefb5..7ebb04c81d7702b94b624c8d1d9904640d840201 100644
--- a/content/common/gpu/image_transport_surface_mac.cc
+++ b/content/common/gpu/image_transport_surface_mac.cc
@@ -270,8 +270,10 @@ gfx::Size IOSurfaceImageTransportSurface::GetSize() {
 }
 
 void IOSurfaceImageTransportSurface::OnBufferPresented(
-    const AcceleratedSurfaceMsg_BufferPresented_Params& /* params */) {
+    const AcceleratedSurfaceMsg_BufferPresented_Params& params) {
   DCHECK(is_swap_buffers_pending_);
+
+  context_->share_group()->SetRendererID(params.renderer_id);
   is_swap_buffers_pending_ = false;
   if (did_unschedule_) {
     did_unschedule_ = false;