Refactor ProcessSingleton so that it may be used distinctly from a full browser process.

chrome/browser/process_singleton.cc

Index: chrome/browser/process_singleton.cc
diff --git a/chrome/browser/process_singleton.cc b/chrome/browser/process_singleton.cc
index dcda573e404dc2de2a6986ef33cb5c313e28e4e3..21c465490210bd22176c108fd80687e52a2baa00 100644
--- a/chrome/browser/process_singleton.cc
+++ b/chrome/browser/process_singleton.cc
@@ -17,7 +17,7 @@ void ProcessSingleton::Unlock() {
       if (replayed_messages.find(*it) !=
           replayed_messages.end())
         continue;
-      ProcessCommandLine(CommandLine(it->first), it->second);
+      notification_callback_.Run(CommandLine(it->first), it->second);
       replayed_messages.insert(*it);
     }
     saved_startup_messages_.clear();