Align the launch location passed to prediction session

Matches the prediction helper (the prediction service ignores added
widgets if launch location doesn't match the pattern. The size / pos
details however aren't used, so we pass defaults.

With this, prediction service may be able to predict widgets that
aren't already added, hence providing more suggestions.

Bug: N/A
Test: Unit test
Flag: EXEMPT BUGFIX
Change-Id: Ieaba4c9a8354dc96ea2bc70cafa106978037c572