QC: Clear action map before reconstructing it

Also, I changed the ActionMultiMap to be a local variable.
1) I figured this enhanced maintainability. This was the only
   object field that was mutated off the main thread. Leaving
   it global could lead to confusion.
2) This is only used in one method

Bug: 15814131
Change-Id: I4e3a315ae2347e2e1e652eb79023b2907f0c7c7e
1 file changed