Fix race in SlowDownloadInterceptor.

SlowDownloadInterceptor can potentially intercept a request in its
constructor before it's finished initializing, which will cause a
segfault. This CL makes sure it's initialized before it can receive
any requests.

Bug: 933963
Change-Id: I58e7db8e423cf052ddbd2cc5fe225695ef2d2325
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1626883
Commit-Queue: Min Qin <qinmin@chromium.org>
Auto-Submit: Robbie McElrath <rmcelrath@chromium.org>
Reviewed-by: Min Qin <qinmin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#663109}
1 file changed