Change GetCanonicalSuffix() interface.

This CL changes the argument of GetCanonicalSuffix() from HostPortPair to
std::string (both const&) to better document the fact that GetCanonicalSuffix
only operates on that field.

BUG=392575

Review URL: https://codereview.chromium.org/868753007

Cr-Commit-Position: refs/heads/master@{#314014}
4 files changed