--- a/mobile/android/base/java/org/mozilla/gecko/ActionBarTextSelection.java
+++ b/mobile/android/base/java/org/mozilla/gecko/ActionBarTextSelection.java
@@ -3,44 +3,46 @@
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 package org.mozilla.gecko;
 
 import org.mozilla.gecko.menu.GeckoMenu;
 import org.mozilla.gecko.menu.GeckoMenuItem;
 import org.mozilla.gecko.util.ResourceDrawableUtils;
 import org.mozilla.gecko.text.TextSelection;
-import org.mozilla.gecko.util.GeckoEventListener;
+import org.mozilla.gecko.util.BundleEventListener;
+import org.mozilla.gecko.util.EventCallback;
+import org.mozilla.gecko.util.GeckoBundle;
 import org.mozilla.gecko.util.ThreadUtils;
 import org.mozilla.gecko.ActionModeCompat.Callback;
 
 import android.content.Context;
 import android.graphics.drawable.Drawable;
 import android.view.MenuItem;
 
-import org.json.JSONArray;
 import org.json.JSONException;
 import org.json.JSONObject;
 
+import java.util.Arrays;
 import java.util.Timer;
 import java.util.TimerTask;
 
 import android.util.Log;
 
-class ActionBarTextSelection implements TextSelection, GeckoEventListener {
+class ActionBarTextSelection implements TextSelection, BundleEventListener {
     private static final String LOGTAG = "GeckoTextSelection";
     private static final int SHUTDOWN_DELAY_MS = 250;
 
     private final Context context;
 
     private boolean mDraggingHandles;
 
-    private String selectionID; // Unique ID provided for each selection action.
+    private int selectionID; // Unique ID provided for each selection action.
 
-    private String mCurrentItems;
+    private GeckoBundle[] mCurrentItems;
 
     private TextSelectionActionModeCallback mCallback;
 
     // These timers are used to avoid flicker caused by selection handles showing/hiding quickly.
     // For instance when moving between single handle caret mode and two handle selection mode.
     private final Timer mActionModeTimer = new Timer("actionMode");
     private class ActionModeTimerTask extends TimerTask {
         @Override
@@ -60,95 +62,79 @@ class ActionBarTextSelection implements 
     }
 
     @Override
     public void create() {
         // Only register listeners if we have valid start/middle/end handles
         if (context == null) {
             Log.e(LOGTAG, "Failed to initialize text selection because at least one context is null");
         } else {
-            GeckoApp.getEventDispatcher().registerGeckoThreadListener(this,
-                "TextSelection:ActionbarInit",
-                "TextSelection:ActionbarStatus",
-                "TextSelection:ActionbarUninit",
-                "TextSelection:Update");
+            GeckoApp.getEventDispatcher().registerUiThreadListener(this,
+                    "TextSelection:ActionbarInit",
+                    "TextSelection:ActionbarStatus",
+                    "TextSelection:ActionbarUninit");
         }
     }
 
     @Override
     public boolean dismiss() {
         // We do not call endActionMode() here because this is already handled by the activity.
         return false;
     }
 
     @Override
     public void destroy() {
         if (context == null) {
             Log.e(LOGTAG, "Do not unregister TextSelection:* listeners since context is null");
         } else {
-            GeckoApp.getEventDispatcher().unregisterGeckoThreadListener(this,
+            GeckoApp.getEventDispatcher().unregisterUiThreadListener(this,
                     "TextSelection:ActionbarInit",
                     "TextSelection:ActionbarStatus",
-                    "TextSelection:ActionbarUninit",
-                    "TextSelection:Update");
+                    "TextSelection:ActionbarUninit");
         }
     }
 
     @Override
-    public void handleMessage(final String event, final JSONObject message) {
-        ThreadUtils.postToUiThread(new Runnable() {
-            @Override
-            public void run() {
-                try {
-                    if (event.equals("TextSelection:Update")) {
-                        if (mActionModeTimerTask != null)
-                            mActionModeTimerTask.cancel();
-                        showActionMode(message.getJSONArray("actions"));
-                    } else if (event.equals("TextSelection:ActionbarInit")) {
-                        // Init / Open the action bar. Note the current selectionID,
-                        // cancel any pending actionBar close.
-                        Telemetry.sendUIEvent(TelemetryContract.Event.SHOW,
-                            TelemetryContract.Method.CONTENT, "text_selection");
+    public void handleMessage(final String event, final GeckoBundle message,
+                              final EventCallback callback) {
+        if ("TextSelection:ActionbarInit".equals(event)) {
+            // Init / Open the action bar. Note the current selectionID,
+            // cancel any pending actionBar close.
+            Telemetry.sendUIEvent(TelemetryContract.Event.SHOW,
+                TelemetryContract.Method.CONTENT, "text_selection");
 
-                        selectionID = message.getString("selectionID");
-                        mCurrentItems = null;
-                        if (mActionModeTimerTask != null) {
-                            mActionModeTimerTask.cancel();
-                        }
+            selectionID = message.getInt("selectionID");
+            mCurrentItems = null;
+            if (mActionModeTimerTask != null) {
+                mActionModeTimerTask.cancel();
+            }
 
-                    } else if (event.equals("TextSelection:ActionbarStatus")) {
-                        // Ensure async updates from SearchService for example are valid.
-                        if (selectionID != message.optString("selectionID")) {
-                            return;
-                        }
-
-                        // Update the actionBar actions as provided by Gecko.
-                        showActionMode(message.getJSONArray("actions"));
+        } else if ("TextSelection:ActionbarStatus".equals(event)) {
+            // Ensure async updates from SearchService for example are valid.
+            if (selectionID != message.getInt("selectionID")) {
+                return;
+            }
 
-                    } else if (event.equals("TextSelection:ActionbarUninit")) {
-                        // Uninit the actionbar. Schedule a cancellable close
-                        // action to avoid UI jank. (During SelectionAll for ex).
-                        mCurrentItems = null;
-                        mActionModeTimerTask = new ActionModeTimerTask();
-                        mActionModeTimer.schedule(mActionModeTimerTask, SHUTDOWN_DELAY_MS);
-                    }
+            // Update the actionBar actions as provided by Gecko.
+            showActionMode(message.getBundleArray("actions"));
 
-                } catch (JSONException e) {
-                    Log.e(LOGTAG, "JSON exception", e);
-                }
-            }
-        });
+        } else if ("TextSelection:ActionbarUninit".equals(event)) {
+            // Uninit the actionbar. Schedule a cancellable close
+            // action to avoid UI jank. (During SelectionAll for ex).
+            mCurrentItems = null;
+            mActionModeTimerTask = new ActionModeTimerTask();
+            mActionModeTimer.schedule(mActionModeTimerTask, SHUTDOWN_DELAY_MS);
+        }
     }
 
-    private void showActionMode(final JSONArray items) {
-        String itemsString = items.toString();
-        if (itemsString.equals(mCurrentItems)) {
+    private void showActionMode(final GeckoBundle[] items) {
+        if (Arrays.equals(items, mCurrentItems)) {
             return;
         }
-        mCurrentItems = itemsString;
+        mCurrentItems = items;
 
         if (mCallback != null) {
             mCallback.updateItems(items);
             return;
         }
 
         if (context instanceof ActionModeCompat.Presenter) {
             final ActionModeCompat.Presenter presenter = (ActionModeCompat.Presenter) context;
@@ -162,84 +148,78 @@ class ActionBarTextSelection implements 
         if (context instanceof ActionModeCompat.Presenter) {
             final ActionModeCompat.Presenter presenter = (ActionModeCompat.Presenter) context;
             presenter.endActionModeCompat();
         }
         mCurrentItems = null;
     }
 
     private class TextSelectionActionModeCallback implements Callback {
-        private JSONArray mItems;
+        private GeckoBundle[] mItems;
         private ActionModeCompat mActionMode;
 
-        public TextSelectionActionModeCallback(JSONArray items) {
+        public TextSelectionActionModeCallback(final GeckoBundle[] items) {
             mItems = items;
         }
 
-        public void updateItems(JSONArray items) {
+        public void updateItems(final GeckoBundle[] items) {
             mItems = items;
             if (mActionMode != null) {
                 mActionMode.invalidate();
             }
         }
 
         public void animateIn() {
             if (mActionMode != null) {
                 mActionMode.animateIn();
             }
         }
 
         @Override
         public boolean onPrepareActionMode(final ActionModeCompat mode, final GeckoMenu menu) {
-            // Android would normally expect us to only update the state of menu items here
-            // To make the js-java interaction a bit simpler, we just wipe out the menu here and recreate all
-            // the javascript menu items in onPrepare instead. This will be called any time invalidate() is called on the
-            // action mode.
+            // Android would normally expect us to only update the state of menu items
+            // here To make the js-java interaction a bit simpler, we just wipe out the
+            // menu here and recreate all the javascript menu items in onPrepare instead.
+            // This will be called any time invalidate() is called on the action mode.
             menu.clear();
 
-            int length = mItems.length();
+            final int length = mItems.length;
             for (int i = 0; i < length; i++) {
-                try {
-                    final JSONObject obj = mItems.getJSONObject(i);
-                    final GeckoMenuItem menuitem = (GeckoMenuItem) menu.add(0, i, 0, obj.optString("label"));
-                    final int actionEnum = obj.optBoolean("showAsAction") ? GeckoMenuItem.SHOW_AS_ACTION_ALWAYS : GeckoMenuItem.SHOW_AS_ACTION_NEVER;
-                    menuitem.setShowAsAction(actionEnum, R.attr.menuItemActionModeStyle);
+                final GeckoBundle obj = mItems[i];
+                final GeckoMenuItem menuitem = (GeckoMenuItem)
+                        menu.add(0, i, 0, obj.getString("label"));
+                final int actionEnum = obj.getBoolean("showAsAction") ?
+                        GeckoMenuItem.SHOW_AS_ACTION_ALWAYS : GeckoMenuItem.SHOW_AS_ACTION_NEVER;
+                menuitem.setShowAsAction(actionEnum, R.attr.menuItemActionModeStyle);
 
-                    final String iconString = obj.optString("icon");
-                    ResourceDrawableUtils.getDrawable(context, iconString, new ResourceDrawableUtils.BitmapLoader() {
-                        @Override
-                        public void onBitmapFound(Drawable d) {
-                            if (d != null) {
-                                menuitem.setIcon(d);
-                            }
+                final String iconString = obj.getString("icon");
+                ResourceDrawableUtils.getDrawable(context, iconString,
+                        new ResourceDrawableUtils.BitmapLoader() {
+                    @Override
+                    public void onBitmapFound(Drawable d) {
+                        if (d != null) {
+                            menuitem.setIcon(d);
                         }
-                    });
-                } catch (Exception ex) {
-                    Log.i(LOGTAG, "Exception building menu", ex);
-                }
+                    }
+                });
             }
             return true;
         }
 
         @Override
         public boolean onCreateActionMode(ActionModeCompat mode, GeckoMenu unused) {
             mActionMode = mode;
             return true;
         }
 
         @Override
         public boolean onActionItemClicked(ActionModeCompat mode, MenuItem item) {
-            try {
-                final JSONObject obj = mItems.getJSONObject(item.getItemId());
-                GeckoAppShell.notifyObservers("TextSelection:Action", obj.optString("id"));
-                return true;
-            } catch (Exception ex) {
-                Log.i(LOGTAG, "Exception calling action", ex);
-            }
-            return false;
+            final GeckoBundle obj = mItems[item.getItemId()];
+            GeckoAppShell.notifyObservers("TextSelection:Action", obj.getString("id"));
+            return true;
         }
 
         // Called when the user exits the action mode
         @Override
         public void onDestroyActionMode(ActionModeCompat mode) {
             mActionMode = null;
             mCallback = null;
             final JSONObject args = new JSONObject();

--- a/mobile/android/base/java/org/mozilla/gecko/text/FloatingToolbarTextSelection.java
+++ b/mobile/android/base/java/org/mozilla/gecko/text/FloatingToolbarTextSelection.java
@@ -16,42 +16,42 @@ import org.json.JSONException;
 import org.json.JSONObject;
 
 import org.mozilla.gecko.EventDispatcher;
 import org.mozilla.gecko.GeckoApp;
 import org.mozilla.gecko.GeckoAppShell;
 import org.mozilla.gecko.Telemetry;
 import org.mozilla.gecko.TelemetryContract;
 import org.mozilla.gecko.gfx.LayerView;
-import org.mozilla.gecko.util.GeckoEventListener;
+import org.mozilla.gecko.util.BundleEventListener;
+import org.mozilla.gecko.util.EventCallback;
+import org.mozilla.gecko.util.GeckoBundle;
 import org.mozilla.gecko.util.ThreadUtils;
 
 import java.util.List;
 
-import ch.boye.httpclientandroidlib.util.TextUtils;
-
 /**
  * Floating toolbar for text selection actions. Only on Android 6+.
  */
 @TargetApi(Build.VERSION_CODES.M)
-public class FloatingToolbarTextSelection implements TextSelection, GeckoEventListener {
+public class FloatingToolbarTextSelection implements TextSelection, BundleEventListener {
     private static final String LOGTAG = "GeckoFloatTextSelection";
 
     // This is an additional offset we add to the height of the selection. This will avoid that the
     // floating toolbar overlays the bottom handle(s).
     private static final int HANDLES_OFFSET_DP = 20;
 
     private final Activity activity;
     private final LayerView layerView;
     private final int[] locationInWindow;
     private final float handlesOffset;
 
     private ActionMode actionMode;
     private FloatingActionModeCallback actionModeCallback;
-    private String selectionID;
+    private int selectionID;
     /* package-private */ Rect contentRect;
 
     public FloatingToolbarTextSelection(Activity activity, LayerView layerView) {
         this.activity = activity;
         this.layerView = layerView;
         this.locationInWindow = new int[2];
 
         this.handlesOffset = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,
@@ -64,17 +64,17 @@ public class FloatingToolbarTextSelectio
             endTextSelection();
             return true;
         }
 
         return false;
     }
 
     private void endTextSelection() {
-        if (TextUtils.isEmpty(selectionID)) {
+        if (selectionID == 0) {
             return;
         }
 
         final JSONObject args = new JSONObject();
         try {
             args.put("selectionID", selectionID);
         } catch (JSONException e) {
             Log.e(LOGTAG, "Error building JSON arguments for TextSelection:End", e);
@@ -90,66 +90,57 @@ public class FloatingToolbarTextSelectio
     }
 
     @Override
     public void destroy() {
         unregisterFromEvents();
     }
 
     private void registerForEvents() {
-        GeckoApp.getEventDispatcher().registerGeckoThreadListener(this,
+        GeckoApp.getEventDispatcher().registerUiThreadListener(this,
                 "TextSelection:ActionbarInit",
                 "TextSelection:ActionbarStatus",
                 "TextSelection:ActionbarUninit",
-                "TextSelection:Update",
                 "TextSelection:Visibility");
     }
 
     private void unregisterFromEvents() {
-        GeckoApp.getEventDispatcher().unregisterGeckoThreadListener(this,
+        GeckoApp.getEventDispatcher().unregisterUiThreadListener(this,
                 "TextSelection:ActionbarInit",
                 "TextSelection:ActionbarStatus",
                 "TextSelection:ActionbarUninit",
-                "TextSelection:Update",
                 "TextSelection:Visibility");
     }
 
-    @Override
-    public void handleMessage(final String event, final JSONObject message) {
-        ThreadUtils.postToUiThread(new Runnable() {
-            @Override
-            public void run() {
-                handleOnMainThread(event, message);
-            }
-        });
-    }
-
-    private void handleOnMainThread(final String event, final JSONObject message) {
+    @Override // BundleEventListener
+    public void handleMessage(final String event, final GeckoBundle message,
+                              final EventCallback callback) {
         if ("TextSelection:ActionbarInit".equals(event)) {
             Telemetry.sendUIEvent(TelemetryContract.Event.SHOW,
                 TelemetryContract.Method.CONTENT, "text_selection");
 
-            selectionID = message.optString("selectionID");
+            selectionID = message.getInt("selectionID");
+
         } else if ("TextSelection:ActionbarStatus".equals(event)) {
             // Ensure async updates from SearchService for example are valid.
-            if (selectionID != message.optString("selectionID")) {
+            if (selectionID != message.getInt("selectionID")) {
                 return;
             }
 
             updateRect(message);
 
             if (!isRectVisible()) {
                 finishActionMode();
             } else {
                 startActionMode(TextAction.fromEventMessage(message));
             }
+
         } else if ("TextSelection:ActionbarUninit".equals(event)) {
             finishActionMode();
-        } else if ("TextSelection:Update".equals(event)) {
-            startActionMode(TextAction.fromEventMessage(message));
+
         } else if ("TextSelection:Visibility".equals(event)) {
             finishActionMode();
         }
     }
 
     private void startActionMode(List<TextAction> actions) {
         if (actionMode != null) {
             actionModeCallback.updateActions(actions);
@@ -178,29 +169,25 @@ public class FloatingToolbarTextSelectio
      */
     private boolean isRectVisible() {
         // There's another case of an empty rect where just left == right but not top == bottom.
         // That's the rect for a collapsed selection. While technically this rect isn't visible too
         // we are not interested in this case because we do not want to hide the toolbar.
         return contentRect.left != contentRect.right || contentRect.top != contentRect.bottom;
     }
 
-    private void updateRect(JSONObject message) {
-        try {
-            final double x = message.getDouble("x");
-            final double y = (int) message.getDouble("y");
-            final double width = (int) message.getDouble("width");
-            final double height = (int) message.getDouble("height");
-
-            final float zoomFactor = layerView.getZoomFactor();
-            layerView.getLocationInWindow(locationInWindow);
+    private void updateRect(final GeckoBundle message) {
+        final double x = message.getDouble("x");
+        final double y = (int) message.getDouble("y");
+        final double width = (int) message.getDouble("width");
+        final double height = (int) message.getDouble("height");
 
-            contentRect = new Rect(
-                    (int) (x * zoomFactor + locationInWindow[0]),
-                    (int) (y * zoomFactor + locationInWindow[1]),
-                    (int) ((x + width) * zoomFactor + locationInWindow[0]),
-                    (int) ((y + height) * zoomFactor + locationInWindow[1] +
-                           (height > 0 ? handlesOffset : 0)));
-        } catch (JSONException e) {
-            Log.w(LOGTAG, "Could not calculate content rect", e);
-        }
+        final float zoomFactor = layerView.getZoomFactor();
+        layerView.getLocationInWindow(locationInWindow);
+
+        contentRect = new Rect(
+                (int) (x * zoomFactor + locationInWindow[0]),
+                (int) (y * zoomFactor + locationInWindow[1]),
+                (int) ((x + width) * zoomFactor + locationInWindow[0]),
+                (int) ((y + height) * zoomFactor + locationInWindow[1] +
+                       (height > 0 ? handlesOffset : 0)));
     }
 }

--- a/mobile/android/base/java/org/mozilla/gecko/text/TextAction.java
+++ b/mobile/android/base/java/org/mozilla/gecko/text/TextAction.java
@@ -5,51 +5,48 @@
 package org.mozilla.gecko.text;
 
 import android.util.Log;
 
 import org.json.JSONArray;
 import org.json.JSONException;
 import org.json.JSONObject;
 
+import org.mozilla.gecko.util.GeckoBundle;
+
 import java.util.ArrayList;
 import java.util.List;
 
 /**
  * Text selection action like "copy", "paste", ..
  */
 public class TextAction {
     private static final String LOGTAG = "GeckoTextAction";
 
     private String id;
     private String label;
     private int order;
     private int floatingOrder;
 
     private TextAction() {}
 
-    public static List<TextAction> fromEventMessage(JSONObject message) {
+    public static List<TextAction> fromEventMessage(final GeckoBundle message) {
         final List<TextAction> actions = new ArrayList<>();
-
-        try {
-            final JSONArray array = message.getJSONArray("actions");
-
-            for (int i = 0; i < array.length(); i++) {
-                final JSONObject object = array.getJSONObject(i);
+        final GeckoBundle[] array = message.getBundleArray("actions");
 
-                final TextAction action = new TextAction();
-                action.id = object.getString("id");
-                action.label = object.getString("label");
-                action.order = object.getInt("order");
-                action.floatingOrder = object.optInt("floatingOrder", i);
+        for (int i = 0; i < array.length; i++) {
+            final GeckoBundle object = array[i];
+            final TextAction action = new TextAction();
 
-                actions.add(action);
-            }
-        } catch (JSONException e) {
-            Log.w(LOGTAG, "Could not parse text actions", e);
+            action.id = object.getString("id");
+            action.label = object.getString("label");
+            action.order = object.getInt("order");
+            action.floatingOrder = object.getInt("floatingOrder", i);
+
+            actions.add(action);
         }
 
         return actions;
     }
 
     public String getId() {
         return id;
     }

--- a/mobile/android/chrome/content/ActionBarHandler.js
+++ b/mobile/android/chrome/content/ActionBarHandler.js
@@ -138,30 +138,30 @@ var ActionBarHandler = {
     }
 
     // Hold the ActionBar ID provided by Gecko.
     this._selectionID = this._nextSelectionID++;
     [this._targetElement, this._contentWindow] = [element, win];
     this._boundingClientRect = boundingClientRect;
 
     // Open the ActionBar, send it's actions list.
-    Messaging.sendRequest({
+    WindowEventDispatcher.sendRequest({
       type: "TextSelection:ActionbarInit",
       selectionID: this._selectionID,
     });
     this._sendActionBarActions(true);
 
     return this.START_TOUCH_ERROR.NONE;
   },
 
   /**
    * Called when content is scrolled and handles are hidden.
    */
   _updateVisibility: function() {
-    Messaging.sendRequest({
+    WindowEventDispatcher.sendRequest({
       type: "TextSelection:Visibility",
       selectionID: this._selectionID,
     });
   },
 
   /**
    * Determines the window containing the selection, and its
    * editable element if present.
@@ -202,17 +202,17 @@ var ActionBarHandler = {
    */
   _uninit: function(clearSelection = true) {
     // Bail if there's no active selection.
     if (!this._selectionID) {
       return;
     }
 
     // Close the ActionBar.
-    Messaging.sendRequest({
+    WindowEventDispatcher.sendRequest({
       type: "TextSelection:ActionbarUninit",
     });
 
     // Clear the selection ID to complete the uninit(), but leave our reference
     // to selectionTargets (_targetElement, _contentWindow) in case we need
     // a final clearSelection().
     this._selectionID = null;
     this._boundingClientRect = null;
@@ -261,17 +261,17 @@ var ActionBarHandler = {
     let actionCountUnchanged = this._actionBarActions &&
       actions.length === this._actionBarActions.length;
     let actionsMatch = actionCountUnchanged &&
       this._actionBarActions.every((e,i) => {
         return e.id === actions[i].id;
       });
 
     if (sendAlways || !actionsMatch) {
-      Messaging.sendRequest({
+      WindowEventDispatcher.sendRequest({
         type: "TextSelection:ActionbarStatus",
         selectionID: this._selectionID,
         actions: actions,
         x: this._boundingClientRect.x,
         y: this._boundingClientRect.y,
         width: this._boundingClientRect.width,
         height: this._boundingClientRect.height
       });