The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/315d17fc22a94a23657b7c52df283f5f93795e89

commit 315d17fc22a94a23657b7c52df283f5f93795e89
Author: jcivelli <jcivelli@chromium.org>
Date: Tue Nov 29 16:15:05 2016

Provide a Mojo equivalent of ThreadSafeSender.

Introduces the ThreadSafeAssociatedInterfacePtrProvider class that
provides functionalities similar to the content::ThreadSafeSender.
You create it with a ChannelProxy and you can then retrieve
ThreadSafeInterfacePtr's from it that you can call methods on from any
thread and even before the actual channel is connected.

BUG= 668317 

Review-Url: https://codereview.chromium.org/2522333002
Cr-Commit-Position: refs/heads/master@{#435005}

[modify] https://crrev.com/315d17fc22a94a23657b7c52df283f5f93795e89/content/renderer/BUILD.gn
[add] https://crrev.com/315d17fc22a94a23657b7c52df283f5f93795e89/content/renderer/mojo/thread_safe_associated_interface_ptr_provider.h
[modify] https://crrev.com/315d17fc22a94a23657b7c52df283f5f93795e89/content/renderer/render_thread_impl.cc
[modify] https://crrev.com/315d17fc22a94a23657b7c52df283f5f93795e89/content/renderer/render_thread_impl.h
[modify] https://crrev.com/315d17fc22a94a23657b7c52df283f5f93795e89/ipc/ipc_channel_proxy.h
[modify] https://crrev.com/315d17fc22a94a23657b7c52df283f5f93795e89/mojo/public/cpp/bindings/tests/associated_interface_unittest.cc
[modify] https://crrev.com/315d17fc22a94a23657b7c52df283f5f93795e89/mojo/public/cpp/bindings/tests/interface_ptr_unittest.cc
[modify] https://crrev.com/315d17fc22a94a23657b7c52df283f5f93795e89/mojo/public/cpp/bindings/thread_safe_interface_ptr.h