Added X-GoogleUpdate-Updater and X-GoogleUpdate-AppId headers to CUS.

As part of the ddos mitigations, implemented all three ddos headers in
the component updater. The base::Optional implementation of the
feature is removed. Instead, the headers are passed using a map of
string to string.

There is an unrelated error handling change to invoke the callback if
for some reason, the caller is passing in no component id in the Update call.

Bug: 813193
Change-Id: I26e86564c13c0a5991027a6612dcdefbf991bfab
Reviewed-on: https://chromium-review.googlesource.com/938636
Reviewed-by: Joshua Pawlicki <[email protected]>
Commit-Queue: Sorin Jianu <[email protected]>
Cr-Commit-Position: refs/heads/master@{#539853}
15 files changed