Add the beginning of a simple window manager that we'll support on Windows.

mash/session/session.cc

Index: mash/session/session.cc
diff --git a/mash/session/session.cc b/mash/session/session.cc
index 8c1e48cdc5143a1610bb438425b1ec4afda286c1..e16e2256270c706f296813252601c4f3c6c1afa2 100644
--- a/mash/session/session.cc
+++ b/mash/session/session.cc
@@ -7,6 +7,7 @@
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/message_loop/message_loop.h"
+#include "mash/common/config.h"
 #include "mash/login/public/interfaces/login.mojom.h"
 #include "services/service_manager/public/cpp/connection.h"
 #include "services/service_manager/public/cpp/connector.h"
@@ -93,7 +94,7 @@ void Session::Create(const service_manager::Identity& remote_identity,
 
 void Session::StartWindowManager() {
   StartRestartableService(
-      "ash",
+      common::GetWindowManagerServiceName(),
       base::Bind(&Session::StartWindowManager,
                  base::Unretained(this)));
 }