Use `privacy_policy_update_callout` feature check

Use feature flag check for showing Privacy Policy
update callout on UI.

ee/app/controllers/ee/application_controller.rb

@@ -6,6 +6,9 @@ module EE
     extend ::Gitlab::Utils::Override
 
     prepended do
+      before_action do
+        push_frontend_feature_flag(:privacy_policy_update_callout)
+      end
       around_action :set_current_ip_address
     end
 

ee/app/helpers/ee/user_callouts_helper.rb

@@ -66,7 +66,7 @@ module EE
     end
 
     def show_privacy_policy_update?
-      !user_dismissed?(PRIVACY_POLICY_UPDATE)
+      ::Feature.enabled?(:privacy_policy_update_callout) && !user_dismissed?(PRIVACY_POLICY_UPDATE)
     end
 
     private

ee/spec/helpers/ee/user_callouts_helper_spec.rb

@@ -171,20 +171,35 @@ describe EE::UserCalloutsHelper do
   describe '.show_privacy_policy_update?' do
     subject { helper.show_privacy_policy_update? }
 
-    context 'when user has not dismissed' do
+    context 'when feature `privacy_policy_update_callout` is disabled' do
       before do
-        allow(helper).to receive(:user_dismissed?).and_return(false)
+        Feature.get(:privacy_policy_update_callout).disable
+        allow(helper).to receive(:user_dismissed?).and_return(true)
       end
 
-      it { is_expected.to be true }
+      it { is_expected.to be false }
     end
 
-    context 'when user dismissed' do
+    context 'when feature `privacy_policy_update_callout` is enabled' do
       before do
-        allow(helper).to receive(:user_dismissed?).and_return(true)
+        Feature.get(:privacy_policy_update_callout).enable
       end
 
-      it { is_expected.to be false }
+      context 'when user has not dismissed' do
+        before do
+          allow(helper).to receive(:user_dismissed?).and_return(false)
+        end
+
+        it { is_expected.to be true }
+      end
+
+      context 'when user dismissed' do
+        before do
+          allow(helper).to receive(:user_dismissed?).and_return(true)
+        end
+
+        it { is_expected.to be false }
+      end
     end
   end
 

spec/controllers/application_controller_spec.rb

@@ -94,14 +94,24 @@ describe ApplicationController do
           request.path = '/-/peek'
         end
 
-        it_behaves_like 'not setting gon variables'
+        # TODO:
+        # remove line below once `privacy_policy_update_callout`
+        # feature flag is removed and `gon` reverts back to
+        # to not setting any variables.
+        it_behaves_like 'setting gon variables'
+        # it_behaves_like 'not setting gon variables'
       end
     end
 
     context 'with json format' do
       let(:format) { :json }
 
-      it_behaves_like 'not setting gon variables'
+      # TODO:
+      # remove line below once `privacy_policy_update_callout`
+      # feature flag is removed and `gon` reverts back to
+      # to not setting any variables.
+      it_behaves_like 'setting gon variables'
+      # it_behaves_like 'not setting gon variables'
     end
   end