[ServiceWorker] Remove blink.mojom.FetchAPIRequest.client_id

blink.mojom.FetchAPIRequest.client_id is not used anywhere so we'd
just remove it now.

BUG=911930

Change-Id: I0f64df6f91daa7d6bd52f2a3815b2f070e0a5291
Reviewed-on: https://chromium-review.googlesource.com/c/1377603
Reviewed-by: Makoto Shimazu <shimazu@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Commit-Queue: Leon Han <leon.han@intel.com>
Cr-Commit-Position: refs/heads/master@{#618134}
7 files changed