cashew: libcurl http fetcher: use default CA certificate path
Modify LibcurlHttpFetcher to use the default CA certificate path instead
of a custom path
Cherrypick change introducing LibcurlHttpFetcher::GetHttpResponseCode
method from update_engine, and augment it with better error logging when
curl_easy_getinfo call fails.
Tweak Service::OnUsageUrlUpdate to make it easier to override the
incoming url.
BUG=chromium-os:8225
TEST=Manual testing. Overrode url to be an https url and performed
requests against https-enabled test server. Observed results in logs.
Change-Id: I7a106cb62385b48fdfc6b49c6042a3c29f92ac9d
Review URL: http://codereview.chromium.org/4203001
3 files changed
