Revert 254541 "Mojo: add scaffolding for request/response support"

Reverting as broke mojo_public_bindings_unittests and
mojo_service_manager_unittests 

> Mojo: add scaffolding for request/response support
> 
> Introduces MessageHeaderWithRequestID, which extends MessageHeader, and a corresponding MessageWithRequestIDBuilder.
> 
> Adds an AcceptWithResponder method to MessageReceiver. The idea is that this will be used by generated proxy code to kick off a request that expects a response. Somehow we will bind a user supplied callback to a MessageReceiver::Accept implementation. Details TBD.
> 
> Internally, Connector might get broken down into two layers: a core pump layer (the code that currently exists) and a router layer that'll be responsible for routing incoming messages to the proper MessageReceiver, either a registered responder or the default incoming receiver.
> 
> R=davemoore@chromium.org
> 
> Review URL: https://codereview.chromium.org/185803002

TBR=darin@chromium.org

Review URL: https://codereview.chromium.org/177853004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254769 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 254769