Remove last usage functions from HostContentSettingsMap

chrome/browser/permissions/permission_manager.cc

 // Copyright 2015 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.
 
 #include "chrome/browser/permissions/permission_manager.h"
 
 #include "base/callback.h"
 #include "chrome/browser/content_settings/host_content_settings_map_factory.h"
 #include "chrome/browser/permissions/permission_context.h"
 #include "chrome/browser/permissions/permission_context_base.h"
@@ skipping 321 matching lines @@
 }
 
 void PermissionManager::RegisterPermissionUsage(PermissionType permission,
                                                 const GURL& requesting_origin,
                                                 const GURL& embedding_origin) {
   // This is required because constant permissions don't have a
   // ContentSettingsType.
   if (IsConstantPermission(permission))
     return;
 
-  HostContentSettingsMapFactory::GetForProfile(profile_)->UpdateLastUsage(
-      requesting_origin,
-      embedding_origin,
-      PermissionTypeToContentSetting(permission));
+  // TODO(tsergeant): Use this for measuring permission usage stats.

[mlamouri (slow - plz ping), 2015/11/09 20:33:13]

I'm confused. How is that method not used if it is actually used here?

[raymes, 2015/11/09 23:07:58]

What I'm trying to say is that the usage information is collected here, but is
never used for anything :)

tsergeant wants to add usage metrics very soon (as in within the next 2 weeks)
so I left this hook in for him to use. This CL removes all the code below it
though, which is not useful for him.

 }
 
 int PermissionManager::SubscribePermissionStatusChange(
     PermissionType permission,
     const GURL& requesting_origin,
     const GURL& embedding_origin,
     const base::Callback<void(PermissionStatus)>& callback) {
   if (subscriptions_.IsEmpty())
     HostContentSettingsMapFactory::GetForProfile(profile_)->AddObserver(this);
 
@@ skipping 65 matching lines @@
     // Add the callback to |callbacks| which will be run after the loop to
     // prevent re-entrance issues.
     callbacks.push_back(
         base::Bind(subscription->callback,
                    ContentSettingToPermissionStatus(new_value)));
   }
 
   for (const auto& callback : callbacks)
     callback.Run();
 }