Plumb network stack information about existence of cached copy
through to error page.  Specifically, add a "stale_copy_in_cache" argument to all of (ordered from Browser->Renderer):
* ResourceMsg_RequestComplete IPC message.
* ResourceDispatcher::OnRequestComplete
* ResourceLoaderBridge::Peer::OnCompletedRequest.
* All subclasses of RLB::P::OnCompleted Request, including WebURLLoaderImpl::context::OnCompletedRequest.
* Blink WebURLError and ResourceError classes (https://codereview.chromium.org/138493002).
* LocalizedError::GetStrings.

This is a paired commit with the blink CL
https://codereview.chromium.org/138493002.  That CL must be landed before this one.

BUG=329620

Review URL: https://codereview.chromium.org/138513002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249527 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249527