r1202869 inadvertently removed the call to OnBrowserLaunch during normal
browser startup. The only remaining use for this function was to create
the browser's DidRunUpdater for normal launches. As a consequence,
post-launch "dr" tracking did not happen until the first rendezvous.

This change fixes "dr" tracking by moving creation of the browser's
DidRunUpdater back into ChromeBrowserMainPartsWin, where it lived until
r479139. This is now possible as a result of removal of the toast in
r1205320.

(cherry picked from commit a8be8325f1ed58c4ec280d1a928e78c500ac7820)

Fixed: 1516887
Change-Id: I5b2852886e4721f7ccc01f9edb3f09d964362958
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5177018
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Auto-Submit: Greg Thompson <grt@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#1244787}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5185337
Commit-Queue: Srinivas Sista <srinivassista@chromium.org>
Owners-Override: Srinivas Sista <srinivassista@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/branch-heads/6099@{#1761}
Cr-Branched-From: e6ee4500f7d6549a9ac1354f8d056da49ef406be-refs/heads/main@{#1217362}