Set navigation mode when taskbar is initialised.

Without this, EdgeBackGestureHandler doesn't know that gesture nav is
enabled until you toggle the setting explicitly.

Bug: 198639199
Test: Manual
Change-Id: Ie732469726318a335401a13f68083256f5b9a231

packages/SystemUI/src/com/android/systemui/navigationbar/TaskbarDelegate.java

@@ -102,7 +102,8 @@ public class TaskbarDelegate implements CommandQueue.Callbacks,
         mDisplayId = displayId;
         mCommandQueue.addCallback(this);
         mOverviewProxyService.addCallback(this);
-        mNavigationModeController.addListener(this);
+        mEdgeBackGestureHandler.onNavigationModeChanged(
+                mNavigationModeController.addListener(this));
         mNavigationBarA11yHelper.registerA11yEventListener(mNavA11yEventListener);
         // Set initial state for any listeners
         updateSysuiFlags();