Remove fake request from DocumentLoader

We only used this to call into FrameFetchContext::DispatchDidReceiveResponse.
Instead, we can simplify that method by removing support for main resources
and inline required pieces to DocumentLoader.

Bug: 855189
Change-Id: Ia814c9b5c3febf357831afebe6e1b6ba32b09d87
Reviewed-on: https://chromium-review.googlesource.com/c/1441791
Commit-Queue: Dmitry Gozman <dgozman@chromium.org>
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Cr-Commit-Position: refs/heads/master@{#629230}
4 files changed