Don't indirect through Blob for codeowners data

Codeowners is a project-only feature, while Blob is shared between a
lot of other contexts. Moving codeowners out of it is a step towards
making that clearer. Eventually, we want to remove Blob#project to
make it clearer still.

app/models/blob.rb

@@ -254,5 +254,3 @@ class Blob < SimpleDelegator
     classes.find { |viewer_class| viewer_class.can_render?(self, verify_binary: verify_binary) }
   end
 end
-
-Blob.prepend_if_ee('EE::Blob')

ee/app/models/ee/blob.rb

-# frozen_string_literal: true
-
-module EE
-  module Blob
-    extend ActiveSupport::Concern
-
-    def owners
-      @owners ||= ::Gitlab::CodeOwners.for_blob(self)
-    end
-  end
-end

ee/app/views/projects/blob/_owners.html.haml

-- return if blob.owners.empty?
+- owners = Gitlab::CodeOwners.for_blob(@project, blob)
+- return if owners.empty?
 
 .well-segment.blob-auxiliary-viewer.file-owner-content.qa-file-owner-content
   = sprite_icon('users', size: 18, css_class: 'icon')
@@ -6,4 +7,4 @@
     = _("Code owners")
   = link_to icon('question-circle'), help_page_path('user/project/code_owners'), title: 'About this feature', target: '_blank'
   :
-  = users_sentence(blob.owners, link_class: 'file-owner-link qa-link-file-owner')
+  = users_sentence(owners, link_class: 'file-owner-link qa-link-file-owner')

ee/lib/gitlab/code_owners.rb

@@ -5,9 +5,9 @@ module Gitlab
     FILE_NAME = 'CODEOWNERS'
     FILE_PATHS = [FILE_NAME, "docs/#{FILE_NAME}", ".gitlab/#{FILE_NAME}"].freeze
 
-    def self.for_blob(blob)
-      if blob.project.feature_available?(:code_owners)
-        Loader.new(blob.project, blob.commit_id, blob.path).members
+    def self.for_blob(project, blob)
+      if project.feature_available?(:code_owners)
+        Loader.new(project, blob.commit_id, blob.path).members
       else
         []
       end

ee/spec/lib/gitlab/code_owners_spec.rb

@@ -29,7 +29,7 @@ describe Gitlab::CodeOwners do
       end
 
       it 'returns users for a blob' do
-        expect(described_class.for_blob(blob)).to include(code_owner)
+        expect(described_class.for_blob(project, blob)).to include(code_owner)
       end
     end
 
@@ -39,7 +39,7 @@ describe Gitlab::CodeOwners do
       end
 
       it 'returns no users' do
-        expect(described_class.for_blob(blob)).to be_empty
+        expect(described_class.for_blob(project, blob)).to be_empty
       end
     end
   end

ee/spec/models/blob_spec.rb

-# frozen_string_literal: true
-
-require 'spec_helper'
-
-describe Blob do
-  let(:project) { create(:project, :repository) }
-  let(:blob) do
-    project.repository.blob_at(TestEnv::BRANCH_SHA['with-codeowners'], 'docs/CODEOWNERS')
-  end
-  let(:code_owner) { create(:user, username: 'documentation-owner') }
-
-  before do
-    project.add_developer(code_owner)
-  end
-
-  describe '#owners' do
-    context 'when the feature is available' do
-      before do
-        stub_licensed_features(code_owners: true)
-      end
-
-      it 'returns the owners from the file' do
-        expect(blob.owners).to include(code_owner)
-      end
-    end
-
-    context 'when the feature is not available' do
-      before do
-        stub_licensed_features(code_owners: false)
-      end
-
-      it 'returns no code owners' do
-        expect(blob.owners).to be_empty
-      end
-    end
-  end
-end