--- a/mobile/android/base/gfx/GeckoLayerClient.java
+++ b/mobile/android/base/gfx/GeckoLayerClient.java
@@ -129,16 +129,17 @@ public class GeckoLayerClient implements
 
         if (windowSizeChanged) {
             Log.d(LOGTAG, "Window-size changed to " + mWindowSize);
         }
 
         GeckoEvent event = GeckoEvent.createSizeChangedEvent(mWindowSize.width, mWindowSize.height,
                                                              mScreenSize.width, mScreenSize.height);
         GeckoAppShell.sendEventToGecko(event);
+        GeckoAppShell.sendEventToGecko(GeckoEvent.createBroadcastEvent("Window:Resize", ""));
     }
 
     public Bitmap getBitmap() {
         return null;
     }
 
     void viewportSizeChanged() {
         // here we send gecko a resize message. The code in browser.js is responsible for

--- a/mobile/android/chrome/content/browser.js
+++ b/mobile/android/chrome/content/browser.js
@@ -3667,45 +3667,42 @@ const kViewportMaxHeight = 10000;
 var ViewportHandler = {
   // The cached viewport metadata for each document. We tie viewport metadata to each document
   // instead of to each tab so that we don't have to update it when the document changes. Using an
   // ES6 weak map lets us avoid leaks.
   _metadata: new WeakMap(),
 
   init: function init() {
     addEventListener("DOMMetaAdded", this, false);
-    addEventListener("resize", this, false);
+    Services.obs.addObserver(this, "Window:Resize", false);
   },
 
   uninit: function uninit() {
     removeEventListener("DOMMetaAdded", this, false);
-    removeEventListener("resize", this, false);
+    Services.obs.removeObserver(this, "Window:Resize", false);
   },
 
   handleEvent: function handleEvent(aEvent) {
     switch (aEvent.type) {
       case "DOMMetaAdded":
         let target = aEvent.originalTarget;
         if (target.name != "viewport")
           break;
         let document = target.ownerDocument;
         let browser = BrowserApp.getBrowserForDocument(document);
         let tab = BrowserApp.getTabForBrowser(browser);
         if (tab && tab.contentDocumentIsDisplayed)
           this.updateMetadata(tab);
         break;
-
-      case "resize":
-        // guard against zero values corrupting our viewport numbers. this happens sometimes
-        // during initialization.
-        if (window.outerWidth == 0 || window.outerHeight == 0)
-          break;
-
-        // check dimensions changed to avoid infinite loop because updateViewportSize
-        // triggers a resize on the content window and will trigger this listener again
+    }
+  },
+
+  observe: function(aSubject, aTopic, aData) {
+    switch (aTopic) {
+      case "Window:Resize":
         if (window.outerWidth == gScreenWidth && window.outerHeight == gScreenHeight)
           break;
 
         let oldScreenWidth = gScreenWidth;
         gScreenWidth = window.outerWidth;
         gScreenHeight = window.outerHeight;
         let tabs = BrowserApp.tabs;
         for (let i = 0; i < tabs.length; i++)