Move WebURLRequest::FetchRequestCacheMode to mojom::FetchCacheMode

This is a preparation for merging the cache mode and WebCachePolicy.

Bug: 453190
Change-Id: I47dea5b1e53163474ec333d09ba9b333a8229eba
Reviewed-on: https://chromium-review.googlesource.com/724941
Commit-Queue: Yutaka Hirano <yhirano@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Takashi Toyoshima <toyoshim@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#510981}
8 files changed