Cast: Adding rtp_ts to EncodedAudioFrame.

Including the rtp_ts in the encoded frame allows a
cleaner code and to re-enable logging which was previously
missing.

Review URL: https://codereview.chromium.org/157733002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249838 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249838