Add GetFullRequestHeaders, from URLRequestJob to HttpNetworkTransaction.

Dev Tools displays the raw request and response headers.  Right now, it gets
them by snarfing them out of the NetLog, which is bad, as the NetLog is for
huamn consumption only.  I'm trying to refactor the DevToolsNetLogObserver
away; providing an alternate, supported path to get the request headers is the
first step.

BUG=196304
TEST=added to URLRequest, HttpTransaction, and HttpNetworkTransaction unittests

Review URL: https://chromiumcodereview.appspot.com/12621011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@199535 0039d316-1c4b-4281-b951-d872f2087c98
18 files changed