adjust method visibility according to it's usage.

`Schema#migrations_paths` is not supposed to be public API. In fact
it's only used inside `Schema` itself, so let's make it private.

activerecord/lib/active_record/schema.rb

@@ -28,24 +28,6 @@ module ActiveRecord
   # ActiveRecord::Schema is only supported by database adapters that also
   # support migrations, the two features being very similar.
   class Schema < Migration
-
-    # Returns the migrations paths.
-    #
-    #   ActiveRecord::Schema.new.migrations_paths
-    #   # => ["db/migrate"] # Rails migration path by default.
-    def migrations_paths
-      ActiveRecord::Migrator.migrations_paths
-    end
-
-    def define(info, &block) # :nodoc:
-      instance_eval(&block)
-
-      if info[:version].present?
-        initialize_schema_migrations_table
-        connection.assume_migrated_upto_version(info[:version], migrations_paths)
-      end
-    end
-
     # Eval the given block. All methods available to the current connection
     # adapter are available within the block, so you can easily use the
     # database definition DSL to build up your schema (+create_table+,
@@ -60,5 +42,23 @@ module ActiveRecord
     def self.define(info={}, &block)
       new.define(info, &block)
     end
+
+    def define(info, &block) # :nodoc:
+      instance_eval(&block)
+
+      if info[:version].present?
+        initialize_schema_migrations_table
+        connection.assume_migrated_upto_version(info[:version], migrations_paths)
+      end
+    end
+
+    private
+      # Returns the migrations paths.
+      #
+      #   ActiveRecord::Schema.new.migrations_paths
+      #   # => ["db/migrate"] # Rails migration path by default.
+      def migrations_paths # :nodoc:
+        ActiveRecord::Migrator.migrations_paths
+      end
   end
 end