Android: Factor out TabState API from Tab

Moves TabState-related stuff from Tab to TabState which is a collection
of static utility methods.

|SHOULD_PRESERVE| is not in use any more. Deleted the field from
TabState, and access to/from Bundle.

Bug: 925242
Change-Id: I675275d821cabcccc5e67eef67baa80a103073a0
Reviewed-by: Theresa <>
Commit-Queue: Jinsuk Kim <>
Cr-Commit-Position: refs/heads/master@{#639704}
8 files changed