Move runner stuff into a runner namespace.

mojo/runner/child_process_host.cc

Index: mojo/runner/child_process_host.cc
diff --git a/mojo/runner/child_process_host.cc b/mojo/runner/child_process_host.cc
index 21986787dd4267c06b6c8975712702c78dfdf1a8..0a06992cf9004378dec6ca355a8076c0eb5c0bef 100644
--- a/mojo/runner/child_process_host.cc
+++ b/mojo/runner/child_process_host.cc
@@ -25,7 +25,7 @@
 #include "ui/gl/gl_switches.h"
 
 namespace mojo {
-namespace shell {
+namespace runner {
 
 ChildProcessHost::ChildProcessHost(Context* context, const std::string& name)
     : context_(context), name_(name), channel_info_(nullptr) {
@@ -159,5 +159,5 @@ void ChildProcessHost::DidCreateChannel(embedder::ChannelInfo* channel_info) {
   channel_info_ = channel_info;
 }
 
-}  // namespace shell
+}  // namespace runner
 }  // namespace mojo