Recreate tab switcher stacks/lists when tabs are merged
If tabs from two instances of are merged while either the StackLayout
or OverviewListLayout is active, recreate the view so that the merged
tabs show up in the layout.
BUG=
602498
Committed:
https://crrev.com/cd0688e84198b95815e29ba6127a1ea0c126a9b8
Cr-Commit-Position: refs/heads/master@{#406945}