--- a/devtools/client/responsive.html/browser/tunnel.js
+++ b/devtools/client/responsive.html/browser/tunnel.js
@@ -141,16 +141,22 @@ function tunnelToInnerBrowser(outer, inn
       // when it creates a new browser, etc.  Since we manually changed the XBL binding
       // above, it caused a fresh webProgress object to be created which does not have any
       // listeners added.  So, we get the listener that gBrowser is using for the tab and
       // reattach it here.
       let tab = gBrowser.getTabForBrowser(outer);
       let filteredProgressListener = gBrowser._tabFilters.get(tab);
       outer.webProgress.addProgressListener(filteredProgressListener);
 
+      // Add the inner browser to tabbrowser's WeakMap from browser to tab.  This assists
+      // with tabbrowser's processing of some events such as MozLayerTreeReady which
+      // bubble up from the remote content frame and trigger tabbrowser to lookup the tab
+      // associated with the browser that triggered the event.
+      gBrowser._tabForBrowser.set(inner, tab);
+
       // All of the browser state from content was swapped onto the inner browser.  Pull
       // this state up to the outer browser.
       for (let property of SWAPPED_BROWSER_STATE) {
         outer[property] = inner[property];
       }
 
       // Wants to access the content's `frameLoader`, so we'll redirect it to
       // inner browser.
@@ -190,26 +196,27 @@ function tunnelToInnerBrowser(outer, inn
         configurable: true,
         enumerable: true,
       });
     }),
 
     stop() {
       let tab = gBrowser.getTabForBrowser(outer);
       let filteredProgressListener = gBrowser._tabFilters.get(tab);
-      browserWindow = null;
-      gBrowser = null;
 
       // The browser's state has changed over time while the tunnel was active.  Push the
       // the current state down to the inner browser, so that it follows the content in
       // case that browser will be swapped elsewhere.
       for (let property of SWAPPED_BROWSER_STATE) {
         inner[property] = outer[property];
       }
 
+      // Remove the inner browser from the WeakMap from browser to tab.
+      gBrowser._tabForBrowser.delete(inner);
+
       // Remove the progress listener we added manually.
       outer.webProgress.removeProgressListener(filteredProgressListener);
 
       // Reset the XBL binding back to the default.
       outer.destroy();
       outer.style.MozBinding = "";
 
       // Reset overridden XBL properties and methods.  Deleting the override
@@ -225,16 +232,19 @@ function tunnelToInnerBrowser(outer, inn
 
       mmTunnel.destroy();
       mmTunnel = null;
 
       // Invalidate outer's permanentKey so that SessionStore stops associating
       // things that happen to the outer browser with the content inside in the
       // inner browser.
       outer.permanentKey = { id: "zombie" };
+
+      browserWindow = null;
+      gBrowser = null;
     },
 
   };
 }
 
 exports.tunnelToInnerBrowser = tunnelToInnerBrowser;
 
 function copyPermanentKey(outer, inner) {