Move Mojo channel initialization closer to IPC::Channel setup

Move Mojo channel initialization closer to IPC::Channel setup

This CL introduces two new content classes:
- MojoApplicationHost encapsulates what's needed to host a Mojo App using Chrome IPC to bootstrap.
- MojoApplication represents what's needed to be a Mojo App using Chrome IPC to bootstrap.

The RenderProcess and RenderProcessHost interfaces are replaced with WebUISetup and WebUISetupClient interfaces. This way the interface is more specific to the service of setting up WebUI.

WebUISetupClient is empty and uninteresting. RenderProcessHostImpl no longer deals with WebUI setup. That is all done directly by RenderViewHostImpl by talking to the WebUISetup service.

Service names get defined in content/common/mojo/mojo_service_names.{h,cc}.

TBR=sky@chromium.org, tsepez@chromium.org
Originally reviewed at https://codereview.chromium.org/236813002/

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=265962

[darin (slow to review), 2014-04-24 18:16:26]

Note, this is just a minor delta from
https://codereview.chromium.org/236813002/, which you already reviewed. The
changes are some additional #ifdefs for the IOS build.

[darin (slow to review), 2014-04-24 18:18:00]

Committed patchset #6 manually as r265962 (presubmit successful).