Fix drag bug.

Previous assumption -- that the drag window was defined at time of
DragState construction -- was false. The window, and hence the
Display, is not known until performDrag. This change delays assigning
DragState.mDisplayContent until the window/Display is known.

Fixes bug 7028203.

Change-Id: I5799005652c484ff0c45ab340ce3b9e4b784883e
2 files changed