Huh, I thought I removed what could be removed here.  Maybe I left some bits.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/aafc8c9148a1a7362425387c58d2262aaecaa5f3

commit aafc8c9148a1a7362425387c58d2262aaecaa5f3
Author: Dana Fried <dfried@chromium.org>
Date: Wed Dec 05 17:54:31 2018

Remove obsolete code re tab close buttons when hovering.

Close button is never shown for inactive tabs in touch mode.
Close button is only shown for inactive tabs not in touch mode based on
tab size. The code basically had no effect.

Bug:  911756 
Change-Id: Ib4032125a53ad7b951abb135aa519f730c3c602a
Reviewed-on: https://chromium-review.googlesource.com/c/1362464
Reviewed-by: Peter Boström <pbos@chromium.org>
Commit-Queue: Dana Fried <dfried@chromium.org>
Cr-Commit-Position: refs/heads/master@{#614018}
[modify] https://crrev.com/aafc8c9148a1a7362425387c58d2262aaecaa5f3/chrome/browser/ui/views/tabs/tab.cc
[modify] https://crrev.com/aafc8c9148a1a7362425387c58d2262aaecaa5f3/chrome/browser/ui/views/tabs/tab_controller.h
[modify] https://crrev.com/aafc8c9148a1a7362425387c58d2262aaecaa5f3/chrome/browser/ui/views/tabs/tab_strip.cc
[modify] https://crrev.com/aafc8c9148a1a7362425387c58d2262aaecaa5f3/chrome/browser/ui/views/tabs/tab_strip.h
[modify] https://crrev.com/aafc8c9148a1a7362425387c58d2262aaecaa5f3/chrome/browser/ui/views/tabs/tab_unittest.cc