Store hostname before address is resolved.

Libjingle when requests for address resolve it will
provide address in hostname:port format. But for resolving an address
we just need |hostname|. After |hostname| is resolved to
an IP address, P2PAsyncAddressResolver must set the original
port number passed in the request. Otherwise libjingle will not
able to use the resolved address as it will have 0 port number.


R=hclam@chromium.org
TBR=sergeyu@chromium.org
BUG=348082

Review URL: https://codereview.chromium.org/185683005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254610 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 254610