Add a HostContentSettingsMap layer for Supervised Users.

chrome/browser/supervised_user/supervised_user_settings_service.h

Index: chrome/browser/supervised_user/supervised_user_settings_service.h
diff --git a/chrome/browser/supervised_user/supervised_user_settings_service.h b/chrome/browser/supervised_user/supervised_user_settings_service.h
index 29bd306b345d2de5d416d33621652ed83d89d106..43f86762aa6df6766dc8ef901eebf5732088d074 100644
--- a/chrome/browser/supervised_user/supervised_user_settings_service.h
+++ b/chrome/browser/supervised_user/supervised_user_settings_service.h
@@ -17,6 +17,7 @@
 #include "components/keyed_service/core/keyed_service.h"
 #include "sync/api/syncable_service.h"
 
+class HostContentSettingsMap;
 class PersistentPrefStore;
 class Profile;
 
@@ -78,6 +79,10 @@ class SupervisedUserSettingsService : public KeyedService,
   // available, or when they change.
   void Subscribe(const SettingsCallback& callback);
 
+  // Register own content settings provider with the specified map.
+  void RegisterContentSettings(

[Bernhard Bauer, 2015/02/26 12:44:58]

Why does the SupervisedUserSettingsService now have to know about the
HostContentSettingsMap? The dependencies should be the other way around:

HostContentSettingsMap (or its embedder, i.e. Profile) -> SupervisedProvider ->
SupervisedUserSettingsService

[knn, 2015/02/26 16:18:56]

HostContentSettingsMap is a component so it cannot depend on the
SupervisedProvider. The SupervisedUserSettingsService seemed like a nice
facilitator for this dependency instead of doing it on a profile.
I just uploaded the cl to check, I'll revert back to using the profile then.

[Bernhard Bauer, 2015/02/26 18:03:54]

Hm, I'm wondering whether we could have an embedder method to insert the
individual providers into the HCSM. I'll talk to vabr@ (who I think owns HCSM
componentization about it).

+      HostContentSettingsMap* host_content_settings_map);
+
   // Activates/deactivates the service. This is called by the
   // SupervisedUserService when it is (de)activated.
   void SetActive(bool active);