Merge branch 'tracking-async-emitter' into 'master'

Switch tracking to use the AsyncEmitter

See merge request gitlab-org/gitlab!16575

lib/gitlab/tracking.rb

@@ -33,7 +33,7 @@ module Gitlab
 
       def snowplow
         @snowplow ||= SnowplowTracker::Tracker.new(
-          SnowplowTracker::Emitter.new(Gitlab::CurrentSettings.snowplow_collector_hostname),
+          SnowplowTracker::AsyncEmitter.new(Gitlab::CurrentSettings.snowplow_collector_hostname, protocol: 'https'),
           SnowplowTracker::Subject.new,
           SNOWPLOW_NAMESPACE,
           Gitlab::CurrentSettings.snowplow_site_id

spec/lib/gitlab/tracking_spec.rb

@@ -49,8 +49,8 @@ describe Gitlab::Tracking do
     it 'can track events' do
       tracker = double
 
-      expect(SnowplowTracker::Emitter).to receive(:new).with(
-        'gitfoo.com'
+      expect(SnowplowTracker::AsyncEmitter).to receive(:new).with(
+        'gitfoo.com', { protocol: 'https' }
       ).and_return('_emitter_')
 
       expect(SnowplowTracker::Tracker).to receive(:new).with(