Enable CORB in AppCacheUpdateJob::UpdateURLLoaderRequest::Start.

r613774 started applying CORB to AppCache requests initiated by
AppCacheSubresourceURLFactory (which covers requests from the renderer
process that are not cached and that fall back to the network).

This CL ensures that CORB is also applied to requests that are trigerred
by AppCache manifest (even without renderer-originated fetches).  Such
requests are initiated by
AppCacheUpdateJob::UpdateURLLoaderRequest::Start.

Bug: 927471
Change-Id: I4e0a8438c646ae7b5e757b48e7d7514e8519c6bb
Reviewed-on: https://chromium-review.googlesource.com/c/1448975
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Reviewed-by: Marijn Kruisselbrink <mek@chromium.org>
Commit-Queue: Ɓukasz Anforowicz <lukasza@chromium.org>
Cr-Commit-Position: refs/heads/master@{#629729}
9 files changed