--- a/mobile/android/base/java/org/mozilla/gecko/BrowserApp.java
+++ b/mobile/android/base/java/org/mozilla/gecko/BrowserApp.java
@@ -190,17 +190,16 @@ import java.util.regex.Pattern;
 import static org.mozilla.gecko.mma.MmaDelegate.NEW_TAB;
 
 public class BrowserApp extends GeckoApp
                         implements ActionModePresenter,
                                    AnchoredPopup.OnVisibilityChangeListener,
                                    BookmarkEditFragment.Callbacks,
                                    BrowserSearch.OnEditSuggestionListener,
                                    BrowserSearch.OnSearchListener,
-                                   DynamicToolbarAnimator.MetricsListener,
                                    DynamicToolbarAnimator.ToolbarChromeProxy,
                                    LayoutInflater.Factory,
                                    LightweightTheme.OnChangeListener,
                                    OnUrlOpenListener,
                                    OnUrlOpenInBackgroundListener,
                                    PropertyAnimator.PropertyAnimationListener,
                                    TabsPanel.TabsLayoutChangeListener,
                                    View.OnKeyListener {
@@ -1664,17 +1663,16 @@ public class BrowserApp extends GeckoApp
     @Override
     protected void initializeChrome() {
         super.initializeChrome();
 
         mDoorHangerPopup.setAnchor(mBrowserToolbar.getDoorHangerAnchor());
         mDoorHangerPopup.setOnVisibilityChangeListener(this);
 
         if (mLayerView != null) {
-            mLayerView.getDynamicToolbarAnimator().addMetricsListener(this);
             mLayerView.getDynamicToolbarAnimator().setToolbarChromeProxy(this);
         }
         setDynamicToolbarEnabled(mDynamicToolbar.isEnabled());
 
         // Intercept key events for gamepad shortcuts
         mLayerView.setOnKeyListener(this);
 
         // Initialize the actionbar menu items on startup for both large and small tablets
@@ -1685,27 +1683,16 @@ public class BrowserApp extends GeckoApp
     }
 
     @Override
     public void onDoorHangerShow() {
         mDynamicToolbar.setVisible(true, VisibilityTransition.ANIMATE);
         super.onDoorHangerShow();
     }
 
-    @Override
-    public void onMetricsChanged(ImmutableViewportMetrics aMetrics) {
-        if (isHomePagerVisible() || mBrowserChrome == null) {
-            return;
-        }
-
-        if (mFormAssistPopup != null) {
-            mFormAssistPopup.onMetricsChanged(aMetrics);
-        }
-    }
-
     // ToolbarChromeProxy inteface
     @Override
     public Bitmap getBitmapOfToolbarChrome() {
         if (mBrowserChrome == null) {
             return null;
         }
 
         Bitmap bm = Bitmap.createBitmap(mBrowserChrome.getWidth(), mBrowserChrome.getHeight(), Bitmap.Config.ARGB_8888);

--- a/mobile/android/base/java/org/mozilla/gecko/FormAssistPopup.java
+++ b/mobile/android/base/java/org/mozilla/gecko/FormAssistPopup.java
@@ -380,29 +380,16 @@ public class FormAssistPopup extends Rel
     void onTranslationChanged() {
         ThreadUtils.assertOnUiThread();
         if (!isShown()) {
             return;
         }
         positionAndShowPopup();
     }
 
-    void onMetricsChanged(final ImmutableViewportMetrics aMetrics) {
-        if (!isShown()) {
-            return;
-        }
-
-        ThreadUtils.postToUiThread(new Runnable() {
-            @Override
-            public void run() {
-                positionAndShowPopup(aMetrics);
-            }
-        });
-    }
-
     private static final class AutoCompleteListAdapter extends ArrayAdapter<Pair<String, String>> {
         private final LayoutInflater mInflater;
         private final int mTextViewResourceId;
 
         public AutoCompleteListAdapter(Context context, int textViewResourceId) {
             super(context, textViewResourceId);
 
             mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

--- a/mobile/android/modules/FormAssistant.jsm
+++ b/mobile/android/modules/FormAssistant.jsm
@@ -110,16 +110,19 @@ var FormAssistant = {
   handleEvent: function(aEvent) {
     switch (aEvent.type) {
       case "focus": {
         let currentElement = aEvent.target;
         // Only show a validation message on focus.
         if (this._showValidationMessage(currentElement) ||
             this._isAutoComplete(currentElement)) {
           this._currentFocusedElement = Cu.getWeakReference(currentElement);
+          // Start listening to resizes.
+          currentElement.ownerGlobal.addEventListener(
+              "resize", this, {capture: true, mozSystemGroup: true, once: true});
         }
         break;
       }
 
       case "blur": {
         let focused = this.focusedElement;
         if (focused) {
           this._hideFormAssistPopup(focused);
@@ -171,16 +174,28 @@ var FormAssistant = {
           }
           // If we're not showing autocomplete suggestions, hide the form assist popup
           this._hideFormAssistPopup(currentElement);
         };
 
         this._showAutoCompleteSuggestions(currentElement, checkResultsInput);
         break;
       }
+
+      case "resize": {
+        let focused = this.focusedElement;
+        if (focused && focused.ownerGlobal == aEvent.target) {
+          // Reposition the popup as if we just stopped pannning.
+          this.observe(null, "PanZoom:StateChange", "NOTHING");
+          // Continue to listen to resizes.
+          focused.ownerGlobal.addEventListener(
+              "resize", this, {capture: true, mozSystemGroup: true, once: true});
+        }
+        break;
+      }
     }
   },
 
   // We only want to show autocomplete suggestions for certain elements
   _isAutoComplete: function(aElement) {
     return (aElement instanceof Ci.nsIDOMHTMLInputElement) &&
            !aElement.readOnly &&
            !this._isDisabledElement(aElement) &&