Fix feedback broken by TracingController change

- Fix ZipString issue. Reverted feedback_utils.cc and h.
- In TracingManager convert trace data into the original feedback
  format.

BUG=326350

Review URL: https://codereview.chromium.org/104713006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239951 0039d316-1c4b-4281-b951-d872f2087c98
Add VLOG when duplicate packet is received (and ignored).

Review URL: https://codereview.chromium.org/106713006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239953 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 239953
Bypass data reduction proxy on 503 responses

BUG=327407

Review URL: https://codereview.chromium.org/107123004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239955 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 239955