OnionSoup: Combine ApplicationCacheHost and ApplicationCacheHostHelper

This CL is a follow-up of crrev.com/c/1637023.
ApplicationCacheHostHelper is merged to ApplicationCacheHost and
ApplicationCacheHost::BindBackend() is added to bind
AppCacheBackend when the main resource is loaded.
ApplicationCacheHostFor{SharedWorker, Frame} are also changed to
inherit ApplicationCacheHost.

When DocumentLoader creates ApplicationCacheHost, it gets
AppCacheType from WebLocalFrameClient and creates
ApplicationCacheHost based on it. If it has kAppCacheForNone,
it just creates ApplicationCacheHost without binding
AppCacheBackend.

It removes application_cache_host_helper.cc/h and
application_cache_host_client.h.

Bug: 950159
Change-Id: I92a50572a776c18d062aa8f1f2057662a9b91f8f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1657951
Reviewed-by: Marijn Kruisselbrink <mek@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Julie Jeongeun Kim <jkim@igalia.com>
Cr-Commit-Position: refs/heads/master@{#671266}
13 files changed