Introduce Identity Service and its initial usage

chrome/browser/profiles/profile_impl.h

Index: chrome/browser/profiles/profile_impl.h
diff --git a/chrome/browser/profiles/profile_impl.h b/chrome/browser/profiles/profile_impl.h
index 56f8b580c4e91842e53a407a250b96339b95d9c9..54093b9ce0309d2847af68e2365c746b9afa8582 100644
--- a/chrome/browser/profiles/profile_impl.h
+++ b/chrome/browser/profiles/profile_impl.h
@@ -196,6 +196,10 @@ class ProfileImpl : public Profile {
   std::unique_ptr<domain_reliability::DomainReliabilityMonitor>
   CreateDomainReliabilityMonitor(PrefService* local_state);
 
+  // Creates an instance of the Identity Service for this Profile, populating it
+  // with the appropriate instances of its dependencies.
+  std::unique_ptr<service_manager::Service> CreateIdentityService();
+
   PrefChangeRegistrar pref_change_registrar_;
 
   base::FilePath path_;