Revert 272998 "Revert 241291 "Fix a long standing leak on cancel..."

Revert 272998 "Revert 241291 "Fix a long standing leak on cancel..."

> Revert 241291 "Fix a long standing leak on cancellation of rende..."
> 
> This caused crashes elsewhere in the loading code.
> 
> BUG=27911
> 
> > Fix a long standing leak on cancellation of renderer-
> > initiated URLRequests.  ResourceDispatcher was not calling
> > peer->OnCompletedRequest on cancellation of async requests,
> > despite it being expected by WebURLLoaderImpl::Context
> > (The only ResourceLoaderBridge::Peer).
> > 
> > This shouldn't impact externally visible behavior at all,
> > other than fixing the leak, because once
> > WebURLLoaderImpl::Context::Cancel() is called, it will never
> > call back into WebURLLoaderImpl.
> > 
> > BUG=328092
> > 
> > Review URL: https://codereview.chromium.org/113893007
> 
> TBR=mmenke@chromium.org
> 
> Review URL: https://codereview.chromium.org/306483009

TBR=mmenke@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=273000

[mmenke, 2014-05-27 18:19:27]

Committed patchset #1 manually as r273000 (tree was closed).