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Updates the tab strips backgrounds with the new vertical ones. Deletes
unused ones @1x. Updates constants specific to each assets: tab overlap
and cap inset.

Bug: 976817
Change-Id: Ida3b95548ac33c0740c2375eb2153f5bafc569e7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1706436Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Commit-Queue: Javier Ernesto Flores Robles <javierrobles@chromium.org>
Cr-Commit-Position: refs/heads/master@{#678286}