GitLab

Top-controls scrolling was missing a couple of key things:
. when the top-controls are completely visible (and no gesture/scroll is
  underway), the height of the Webcontents should shrink.
. DoBrowserControlsShrinkRendererSize() should not change value while
  a gesture/scroll is underway (otherwise the scrollbar bounces around).

The logic added should match that of Chrome.

BUG=1017204
TEST=none

Change-Id: I2185409244e278dfd230499b65ed2d953eda6d70
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1880589
Commit-Queue: Scott Violet <sky@chromium.org>
Reviewed-by: Bo <boliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#709559}