Add a new GetInstance() method for singleton classes under chrome/service and /net.

chrome/service/service_main.cc

Index: chrome/service/service_main.cc
diff --git a/chrome/service/service_main.cc b/chrome/service/service_main.cc
index 96e7ea66b44f222f9f98765d59e0c359fce3bc01..366021b321e20689872df37191c5db9147120138 100644
--- a/chrome/service/service_main.cc
+++ b/chrome/service/service_main.cc
@@ -17,7 +17,7 @@
 // Mainline routine for running as the service process.
 int ServiceProcessMain(const MainFunctionParams& parameters) {
   // If there is already a service process running, quit now.
-  if (!Singleton<ServiceProcessState>::get()->Initialize())
+  if (!ServiceProcessState::GetInstance()->Initialize())
     return 0;
 
   MessageLoopForUI main_message_loop;