--- a/devtools/server/actors/webbrowser.js
+++ b/devtools/server/actors/webbrowser.js
@@ -23,16 +23,17 @@ Cu.import("resource://gre/modules/XPCOMU
 loader.lazyRequireGetter(this, "RootActor", "devtools/server/actors/root", true);
 loader.lazyRequireGetter(this, "ThreadActor", "devtools/server/actors/script", true);
 loader.lazyRequireGetter(this, "unwrapDebuggerObjectGlobal", "devtools/server/actors/script", true);
 loader.lazyRequireGetter(this, "BrowserAddonActor", "devtools/server/actors/addon", true);
 loader.lazyRequireGetter(this, "WorkerActorList", "devtools/server/actors/worker", true);
 loader.lazyRequireGetter(this, "ServiceWorkerRegistrationActorList", "devtools/server/actors/worker", true);
 loader.lazyRequireGetter(this, "ProcessActorList", "devtools/server/actors/process", true);
 loader.lazyImporter(this, "AddonManager", "resource://gre/modules/AddonManager.jsm");
+loader.lazyImporter(this, "ExtensionContent", "resource://gre/modules/ExtensionContent.jsm");
 
 // Assumptions on events module:
 // events needs to be dispatched synchronously,
 // by calling the listeners in the order or registration.
 loader.lazyRequireGetter(this, "events", "sdk/event/core");
 
 loader.lazyRequireGetter(this, "StyleSheetActor", "devtools/server/actors/stylesheets", true);
 
@@ -713,17 +714,19 @@ function TabActor(aConnection)
   this._sources = null;
 
   // Map of DOM stylesheets to StyleSheetActors
   this._styleSheetActors = new Map();
 
   this._shouldAddNewGlobalAsDebuggee = this._shouldAddNewGlobalAsDebuggee.bind(this);
 
   this.makeDebugger = makeDebugger.bind(null, {
-    findDebuggees: () => this.windows,
+    findDebuggees: () => {
+      return this.windows.concat(this.webextensionsContentScriptGlobals);
+    },
     shouldAddNewGlobalAsDebuggee: this._shouldAddNewGlobalAsDebuggee
   });
 
   // Flag eventually overloaded by sub classes in order to watch new docshells
   // Used on b2g to catch activity frames and in chrome to list all frames
   this.listenForNewDocShells = Services.appinfo.processType == Services.appinfo.PROCESS_TYPE_CONTENT;
 
   this.traits = {
@@ -801,16 +804,29 @@ TabActor.prototype = {
       return this.docShell
         .QueryInterface(Ci.nsIInterfaceRequestor)
         .getInterface(Ci.nsIDOMWindow);
     }
     return null;
   },
 
   /**
+   * Getter for the WebExtensions ContentScript globals related to the
+   * current tab content's DOM window.
+   */
+  get webextensionsContentScriptGlobals() {
+    // Ignore xpcshell runtime which spawn TabActors without a window.
+    if (this.window) {
+      return ExtensionContent.getContentScriptGlobalsForWindow(this.window);
+    }
+
+    return [];
+  },
+
+  /**
    * Getter for the list of all content DOM windows in this tabActor
    * @return {Array}
    */
   get windows() {
     return this.docShells.map(docShell => {
       return docShell.QueryInterface(Ci.nsIInterfaceRequestor)
                      .getInterface(Ci.nsIDOMWindow);
     });