DevTools: move DevToolsAgent/Client into content.

BUG=84078
TEST=

Review URL: http://codereview.chromium.org/7461019

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@93596 0039d316-1c4b-4281-b951-d872f2087c98
void RenderThread::AddRoute(int32 routing_id,
                            IPC::Channel::Listener* listener) {
  widget_count_++;
  return ChildThread::AddRoute(routing_id, listener);
}

void RenderThread::AddRoute(int32 routing_id,
                            IPC::Channel::Listener* listener) {
  widget_count_++;
  return ChildThread::AddRoute(routing_id, listener);
}
