Add a new GetInstance() method for remaining files with singleton classes under chrome/browser.

chrome/browser/upgrade_detector.cc

Index: chrome/browser/upgrade_detector.cc
diff --git a/chrome/browser/upgrade_detector.cc b/chrome/browser/upgrade_detector.cc
index 539c20a853127c4628e077c5907871e68913418a..82438cb8a9c9dfb93843588d82c0ebddba930d15 100644
--- a/chrome/browser/upgrade_detector.cc
+++ b/chrome/browser/upgrade_detector.cc
@@ -167,6 +167,11 @@ UpgradeDetector::UpgradeDetector()
 UpgradeDetector::~UpgradeDetector() {
 }
 
+// static
+UpgradeDetector* UpgradeDetector::GetInstance() {
+  return Singleton<UpgradeDetector>::get();
+}
+
 void UpgradeDetector::CheckForUpgrade() {
   method_factory_.RevokeAll();
   Task* callback_task =