Inline HOST_RESOLER_IMPL_REQUESTs into their parent source

Inlining HOST_RESOLVER_IMPL_REQUESTs into their parent source, rather making
them a top level object. This is to make net-internals cleaner, since the requests
aren't too interesting, it's the HOST_RESOLVER_IML_JOBs that do the actual
resolution.

A side benefit of this cleanup is that in chrome://tracing, netlog data will
be cleaner.

BUG=428786

Review URL: https://codereview.chromium.org/693003002

Cr-Commit-Position: refs/heads/master@{#303477}
10 files changed