Remove ExecutionContext dependency from willSendRequest() etc. probes

This CL removes ExecutionContext from the following probe methods,
and instead passes CoreProbeSink:
- prepareRequest()
- didBlockRequest()
- willSendRequest()
- willSendNavigationRequest()

The ExecutionContext was simply not used, except for
ExecutionContext::Url() inside willSendRequest().
This CL calls FetchContext::Url() at the caller and
pass the URL instead of the whole ExecutionContext.

After this CL, all probe calls from WorkerFetchContext
no longer take WorkerGlobalScope as their argument,
which is good for separating WorkerFetchContext from
WorkerGlobalScope for off-the-main-thread fetch.

Bug: 880027
Change-Id: Idb648c9d809ca6fd95de090fa3b7249b7bb71b9e
Reviewed-on: https://chromium-review.googlesource.com/c/1383911
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Commit-Queue: Hiroshige Hayashizaki <hiroshige@chromium.org>
Cr-Commit-Position: refs/heads/master@{#633959}
10 files changed