Introduce Identity Service and its initial usage

chrome/browser/profiles/profile_impl.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This class gathers state related to a single user profile.
 
 #ifndef CHROME_BROWSER_PROFILES_PROFILE_IMPL_H_
 #define CHROME_BROWSER_PROFILES_PROFILE_IMPL_H_
 
 #include <memory>
@@ skipping 178 matching lines @@
 
   void GetCacheParameters(bool is_media_context,
                           base::FilePath* cache_path,
                           int* max_size);
 
   PrefProxyConfigTracker* CreateProxyConfigTracker();
 
   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();

[msarda, 2017/03/23 10:48:57]

Is it the goal to add the services as part of the Profile object. On downside I
can think of is that this will not work on iOS.

[blundell, 2017/03/24 09:37:59]

It's neither a goal nor a non-goal, but is a tool that can be used when
necessary. In this case it's necessary because the Identity Service needs to be
passed per-Profile classes on its creation. When bringing up services on iOS,
we'll add a corresponding mechanism to attach service creation to
ChromeBrowserState.

In the long term, the Identity Service will be able to instantiate the classes
that it needs internally, because there won't be any other direct consumers of
those classes. Once we've reached that point (which is far down the road
obviously), the Identity Service won't need to be created by the Profile
anymore.

+
   PrefChangeRegistrar pref_change_registrar_;
 
   base::FilePath path_;
   base::FilePath base_cache_path_;
 
   // !!! BIG HONKING WARNING !!!
   //  The order of the members below is important. Do not change it unless
   //  you know what you're doing. Also, if adding a new member here make sure
   //  that the declaration occurs AFTER things it depends on as destruction
   //  happens in reverse order of declaration.
@@ skipping 64 matching lines @@
   // components/keyed_service/content/browser_context_keyed_service_factory.*
 
   Profile::Delegate* delegate_;
 
   chrome_browser_net::Predictor* predictor_;
 
   DISALLOW_COPY_AND_ASSIGN(ProfileImpl);
 };
 
 #endif  // CHROME_BROWSER_PROFILES_PROFILE_IMPL_H_