add auto resize back in if no post message to resize is received

fixes: PLAT-688

test-plan:
*install the test tool
*the test tool frame size should be the full length of the screen

*put in the value you want to resize the tool to.
*it should resize

Change-Id: Ifb04ce49272d83d3f0c58ec40d896d7b443b9ad7
Reviewed-on: https://gerrit.instructure.com/43077
Reviewed-by: Brad Humphrey <brad@instructure.com>
QA-Review: August Thornton <august@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Nathan Mills <nathanm@instructure.com>