move `lib/ci/mask_secret.rb` into `lib/gitlab/ci/mask_secret.rb`

app/models/ci/build.rb

@@ -446,8 +446,8 @@ module Ci
       return unless trace
 
       trace = trace.dup
-      Ci::MaskSecret.mask!(trace, project.runners_token) if project
-      Ci::MaskSecret.mask!(trace, token)
+      Gitlab::Ci::MaskSecret.mask!(trace, project.runners_token) if project
+      Gitlab::Ci::MaskSecret.mask!(trace, token)
       trace
     end
 

lib/ci/mask_secret.rb → lib/gitlab/ci/mask_secret.rb

-module Ci::MaskSecret
+module Gitlab
+  module Ci::MaskSecret
     class << self
       def mask!(value, token)
         return value unless value.present? && token.present?
@@ -7,4 +8,5 @@ module Ci::MaskSecret
         value
       end
     end
+  end
 end

spec/lib/ci/mask_secret_spec.rb → spec/lib/gitlab/ci/mask_secret_spec.rb

 require 'spec_helper'
 
-describe Ci::MaskSecret do
+describe Gitlab::Ci::MaskSecret do
   subject { described_class }
 
   describe '#mask' do