Make draft loading happen on serial executor

This fixes an issue where it loads drafts too quickly on orientation
change (and a previous save has not completed). The save was explicitly
put on the serial executor for this reason, but the load task was
missed. whoops.

Bug: 5361711
Change-Id: Ic764e15deb7cd8b88fa4f87e7cbdf435d7d79c80
1 file changed