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

net/url_request/https_prober.cc

Index: net/url_request/https_prober.cc
diff --git a/net/url_request/https_prober.cc b/net/url_request/https_prober.cc
index 4388294feb90619b965890bcd75d1d2b1ff21987..97022d61b39f9f59fbd3dece9a2d42605d074890 100644
--- a/net/url_request/https_prober.cc
+++ b/net/url_request/https_prober.cc
@@ -15,6 +15,11 @@ HTTPSProber::HTTPSProber() {
 HTTPSProber::~HTTPSProber() {
 }
 
+// static
+HTTPSProber* HTTPSProber::GetInstance() {
+  return Singleton<HTTPSProber>::get();
+}
+
 bool HTTPSProber::HaveProbed(const std::string& host) const {
   return probed_.find(host) != probed_.end();
 }