Stop processing if the new control equals the current one

InsetsSourceConsumer#setControl compares the identities between the new
control and current one. If they are the same, the function stops
processing. However, the instance of the control returned from relayout
will always be different, which makes setControl process more than
expected.

This CL overrides InsetsSourceControl#equals, and use it to decide if we
should do further processing in setControl.

Bug: 185193241
Fix: 185460364
Test: steps in the bug
Change-Id: If347df353202ef441b57dabccfd0ef254ec72477