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

chrome/browser/renderer_host/render_view_host.cc

Index: chrome/browser/renderer_host/render_view_host.cc
diff --git a/chrome/browser/renderer_host/render_view_host.cc b/chrome/browser/renderer_host/render_view_host.cc
index 66ad56451fc7b3b19b0e53924b1a006b10e11467..e5537f8050e5dcaac60b2abcfe29967855ea5918 100644
--- a/chrome/browser/renderer_host/render_view_host.cc
+++ b/chrome/browser/renderer_host/render_view_host.cc
@@ -153,7 +153,7 @@ RenderViewHost::~RenderViewHost() {
   delegate()->RenderViewDeleted(this);
 
   // Be sure to clean up any leftover state from cross-site requests.
-  Singleton<CrossSiteRequestManager>()->SetHasPendingCrossSiteRequest(
+  CrossSiteRequestManager::GetInstance()->SetHasPendingCrossSiteRequest(
       process()->id(), routing_id(), false);
 }
 
@@ -368,7 +368,7 @@ void RenderViewHost::ClosePageIgnoringUnloadEvents() {
 
 void RenderViewHost::SetHasPendingCrossSiteRequest(bool has_pending_request,
                                                    int request_id) {
-  Singleton<CrossSiteRequestManager>()->SetHasPendingCrossSiteRequest(
+  CrossSiteRequestManager::GetInstance()->SetHasPendingCrossSiteRequest(
       process()->id(), routing_id(), has_pending_request);
   pending_request_id_ = request_id;
 }