Add a new GetInstance() method for singleton classes used in chrome/browser files.

chrome/browser/cross_site_request_manager.cc

Index: chrome/browser/cross_site_request_manager.cc
diff --git a/chrome/browser/cross_site_request_manager.cc b/chrome/browser/cross_site_request_manager.cc
index 4104398f1996c7d81b8e518cd7ae3983884dc9da..d12e9a4192ad8d61477bd4bdef6eebc8e48331da 100644
--- a/chrome/browser/cross_site_request_manager.cc
+++ b/chrome/browser/cross_site_request_manager.cc
@@ -4,6 +4,8 @@
 
 #include "chrome/browser/cross_site_request_manager.h"
 
+#include "base/singleton.h"
+
 bool CrossSiteRequestManager::HasPendingCrossSiteRequest(int renderer_id,
                                                          int render_view_id) {
   AutoLock lock(lock_);
@@ -29,3 +31,8 @@ void CrossSiteRequestManager::SetHasPendingCrossSiteRequest(int renderer_id,
 CrossSiteRequestManager::CrossSiteRequestManager() {}
 
 CrossSiteRequestManager::~CrossSiteRequestManager() {}
+
+// static
+CrossSiteRequestManager* CrossSiteRequestManager::GetInstance() {
+  return Singleton<CrossSiteRequestManager>::get();
+}