Continue layout if needed

Sometimes the operations in the deferLayout~continueLayout don't
change significant states related to layout.

This reduces 1~3 times performSurfacePlacement when switching between
activities. Also reduce lots of invocations when resizing task/stack.
Bounds change isn't a layout reason from activity aspect because there
are already many invocations from relayoutWindow, finishDrawingWindow
and animate that will request traversal.

Test: go/wm-smoke
Test: Enable debug log in WindowSurfacePlacer to observe the
      invocation of performSurfacePlacement from continueLayout.
Bug: 140407614

Change-Id: I347f1fe1db676dcf320163bed0df693775b5f022