Backed out 3 changesets (bug 1479569) for devtools/client/responsive.html failures. CLOSED TREE

Backed out changeset e123d0aa911c (bug 1479569)
Backed out changeset b828a58404e5 (bug 1479569)
Backed out changeset 97041ef8f311 (bug 1479569)

toolkit/components/extensions/extension-process-script.js

@@ -88,6 +88,16 @@ var contentScripts = new DefaultWeakMap(matcher => {
                                      matcher);
 });
 
+function getMessageManager(window) {
+  let docShell = window.docShell.QueryInterface(Ci.nsIInterfaceRequestor);
+  try {
+    return docShell.getInterface(Ci.nsIContentFrameMessageManager);
+  } catch (e) {
+    // Some windows don't support this interface (hidden window).
+    return null;
+  }
+}
+
 var DocumentManager;
 var ExtensionManager;
 
@@ -480,7 +490,7 @@ ExtensionProcessScript.prototype = {
   },
 
   initExtensionDocument(policy, doc) {
-    if (DocumentManager.globals.has(doc.defaultView.docShell.messageManager)) {
+    if (DocumentManager.globals.has(getMessageManager(doc.defaultView))) {
       DocumentManager.loadInto(policy, doc.defaultView);
     }
   },
@@ -497,7 +507,7 @@ ExtensionProcessScript.prototype = {
   },
 
   loadContentScript(contentScript, window) {
-    if (DocumentManager.globals.has(window.docShell.messageManager)) {
+    if (DocumentManager.globals.has(getMessageManager(window))) {
       contentScripts.get(contentScript).injectInto(window);
     }
   },