make permission_cache_key_for shard aware

fixes: CNVS-13917

Moves the initializer from active record base to an alias method chain
on AdheresToPolicy::Instance methods.  The way its including the
instance methods did not allow it to override the
permission_cache_key_for method.

Test Case:

  - Flush cache
  - Open a Course
  - Look at the cache keys and all the ids should be global ids

Change-Id: Iac6a5ed95a800c27bd53fcb757cabd11976aef21
Reviewed-on: https://gerrit.instructure.com/37226
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
QA-Review: Jeremy Putnam <jeremyp@instructure.com>
Product-Review: Nick Cloward <ncloward@instructure.com>

config/initializers/active_record.rb

@@ -145,11 +145,6 @@ class ActiveRecord::Base
     @global_asset_string ||= "#{self.class.reflection_type_name}_#{global_id}"
   end
 
-  # Override the adheres_to_policy permission_cache_key for to make it shard aware.
-  def permission_cache_key_for(user, session, right)
-    Shard.default.activate { super }
-  end
-
   # little helper to keep checks concise and avoid a db lookup
   def has_asset?(asset, field = :context)
     asset.id == send("#{field}_id") && asset.class.base_ar_class.name == send("#{field}_type")

config/initializers/adheres_to_policy.rb

@@ -1,2 +1,15 @@
 require 'adheres_to_policy'
-ActiveRecord::Base.send :extend, AdheresToPolicy::ClassMethods
+
+ActiveRecord::Base.send :extend, AdheresToPolicy::ClassMethods
+
+module AdheresToPolicy::InstanceMethods
+
+  # Override the adheres_to_policy permission_cache_key for to make it shard aware.
+  def permission_cache_key_for_with_sharding(user, session, right)
+    Shard.default.activate do
+      permission_cache_key_for_without_sharding(user, session, right)
+    end
+  end
+  alias_method_chain :permission_cache_key_for, :sharding
+
+end

gems/adheres_to_policy/lib/adheres_to_policy/instance_methods.rb

@@ -325,7 +325,6 @@ module AdheresToPolicy
 
       value = some_array.collect { |element| ActiveSupport::Cache.expand_cache_key(element) }.to_param
       some_array.instance_variable_set("@cache_key",  value) unless some_array.frozen?
-      value
 
       some_array.collect { |element| ActiveSupport::Cache.expand_cache_key(element) }.to_param
     end