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

content/browser/renderer_host/render_widget_host_view_mac.mm

Index: content/browser/renderer_host/render_widget_host_view_mac.mm
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.mm b/content/browser/renderer_host/render_widget_host_view_mac.mm
index 7819fe3120fa6ecb9f47038dd07791c14aeff6f6..a64dfc00ffb677481f8a11e317a24a01fa96e871 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/content/browser/renderer_host/render_widget_host_view_mac.mm
@@ -1125,6 +1125,8 @@ void RenderWidgetHostViewMac::AckPendingSwapBuffers() {
     if (pending_swap_buffers_acks_.front().first != 0) {
       AcceleratedSurfaceMsg_BufferPresented_Params ack_params;
       ack_params.sync_point = 0;
+      if (compositing_iosurface_.get())
+        ack_params.renderer = compositing_iosurface_->GetRenderer();
       RenderWidgetHostImpl::AcknowledgeBufferPresent(
           pending_swap_buffers_acks_.front().first,
           pending_swap_buffers_acks_.front().second,