Fix a couple issues with tracking launch cookies

- Fix NPE when there is no running task
- Fix issue where we were defaulting to a prediction icon when
  there was no launch cookie
- Don't use a launch cookie when we are launching from a non-workspace
  item, just fallback to the package name matching in that case

Fixes: 186653036
Fixes: 186593373
Test: Swipe up from various apps launched from predictions, also
      launch an app from all apps and swipe up and ensure it
      doesn't match a prediction
Change-Id: Ie8f5da010c140a5056045ac268d082c80271ab68