Pepper: PPB_Mojo prototype.

Pepper: PPB_Mojo prototype.

This change adds an interface to Pepper for requesting a "bootstrap"
MojoPlatformHandle from the browser. The plugin can use that MojoHandle to
create a channel and connect to Mojo services in the browser.

The plan is for the plugin to request all mojo services to a host in the
browser. The browser can then establish a Mojo MessagePipe with another
process, but send one end of the pipe to the plugin it can use.

Much of this is Pepper plumbing; the most interesting files are:
content/browser/renderer_host/pepper/pepper_mojo_host.cc
ppapi/examples/mojo/mojo.cc

BUG=414804

[teravest, 2014-09-24 20:55:55]

Patchset #1 (id:1) has been deleted