GitLab

This CL reworks the interop mechanism for obtaining version info
from VersionHandler in about:version.  Instead of relying on
chrome.send to result in several asynchronous callbacks, the
parts are requested using cr.sendWithPromise and handlers are
explicitly called by JS.  The original chrome.send mechanism
is left intact for use by platform-specific derived classes.

Bug: 964528

Change-Id: Ia68e95beb68b38201d29d5d51448ee989bdf333f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1717483Reviewed-by: Peter Lee <pkl@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Reviewed-by: Tommy Li <tommycli@chromium.org>
Commit-Queue: Orin Jaworski <orinj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#682332}