for #498 add onboarding-3-security.png asset

remove tab.create orientation

study.js

@@ -4,7 +4,6 @@
 
 const self = require("sdk/self");
 const { when: unload } = require("sdk/system/unload");
-const tabs = require("sdk/tabs");
 
 const shield = require("./lib/shield/index");
 
@@ -25,16 +24,6 @@ class ContainersStudy extends shield.Study {
     // Test Pilot experiment, so exclude them.
     return super.isEligible();
   }
-
-  whenEligible () {
-  }
-
-  whenInstalled () {
-    tabs.open(`data:text/html, Thank you for helping us study Containers in Firefox. You are in the ${this.variation} variation.`);
-  }
-
-  cleanup() {
-  }
 }
 
 const thisStudy = new ContainersStudy(studyConfig);

webextension/popup.html

@@ -47,7 +47,7 @@ <h3 class="onboarding-title">A place for everything, and everything in its place
   </div>
 
   <div class="panel onboarding security-onboarding-panel-3 hide">
-    <img class="onboarding-img" alt="How Containers Work" src="/img/security-onboarding-3.png" />
+    <img class="onboarding-img" alt="How Containers Work" src="/img/onboarding-3-security.png" />
     <h3 class="onboarding-title">Use containers to secure everything within.</h3>
     <p>Containers separate cookies and sensitive data from other containers, like surrounded by firewalls to block tracking.</p>
     <a href="#" class="onboarding-button onboarding-almost-done-button">Next</a>