[ServiceWorker] Move ServiceWorkerFetchEventResult to be used only in browser code

enum ServiceWorkerFetchEventResult does not have to be a common type for
both browser and renderer code, this CL moves it out of
content/common/service_worker/service_worker_types.h, and also removes
the unnecessary IPC traits for it from
content/common/service_worker/service_worker_messages.h.

BUG=789854
TBR=tsepez@chromium.org

Change-Id: I6bda299731b71b8b5f9c493b1a785b7f9889f45b
Reviewed-on: https://chromium-review.googlesource.com/799551
Commit-Queue: Han Leon <leon.han@intel.com>
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#520834}
9 files changed