Revert 232312 "Cleanup ResourceFetcher in preparation to add to ..."

Seems to cause ResourceFetcherTests.ResourceFetcherDeletedInCallback
to timeout on Windows and crash on Linux.

> Cleanup ResourceFetcher in preparation to add to public content API,
> in preparation to move error page logic from content to chrome:
> 
> * Merge ResourceFetcher and ResourceFetcherWithTimeout.
> * Remove unnecessary member variables.
> * Remove Cancel() (All consumers were deleting and cancelling at the
>     same time, anyways, and deleting already cancels).
> * Make definition order match declaration order.
> * Fix outdated comments.
> 
> BUG=308232
> 
> Review URL: https://codereview.chromium.org/33363003

TBR=mmenke@chromium.org

Review URL: https://codereview.chromium.org/55963002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232369 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 232369