Implement sideload wipeout for Extensions.

chrome/browser/resources/extensions/extensions.js

Index: chrome/browser/resources/extensions/extensions.js
===================================================================
--- chrome/browser/resources/extensions/extensions.js	(revision 162977)
+++ chrome/browser/resources/extensions/extensions.js	(working copy)
@@ -252,6 +252,15 @@
       $('toggle-dev-on').disabled = false;
     }
 
+    if (extensionsData.showDisabledExtensionsWarning) {
+      pageDiv.classList.add('showing-banner');
+      pageDiv.classList.add('sideload-wipeout');
+
+      // If we have two banners showing, make sure to have the room for both.
+      if (pageDiv.classList.contains('managed-mode'))
+        pageDiv.style.marginTop = '105px';
+    }
+
     if (extensionsData.developerMode && !extensionsData.managedMode) {
       pageDiv.classList.add('dev-mode');
       $('toggle-dev-on').checked = true;