Revert 248648 "Cache feedback reports to disk in case of send fa..."

BUG=345805

> Cache feedback reports to disk in case of send failure.
> 
> R=zork@chromium.org
> BUG=249853
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=246992
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=247772
> 
> Review URL: https://codereview.chromium.org/141433011

TBR=rkc@chromium.org

Review URL: https://codereview.chromium.org/174313005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252669 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252669