Remove ThreadableLoaderClient argument from WillSendEventSourceRequest

Bug: 880027
Change-Id: Ief7c4a5523cb29212a2f4407124ec87114cd2051
Reviewed-on: https://chromium-review.googlesource.com/c/1383913
Commit-Queue: Hiroshige Hayashizaki <hiroshige@chromium.org>
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#634109}
4 files changed