Prevent taskbar on phone from crashing

* Update code behind flag to work with transient taskbar
* We explicitly set the mDestroyed flag to false in
TaskbarActivityContext because it gets set to true when
the flag is on, but nothing resets it unless it gets
recreated normally.

Bug: 274517647
Flag: persist.wm.debug.hide_navbar_window
Test: Enable flag and verify no crash
Change-Id: I9a149ffb47a10efedfc9dff8399d12d4c1a31553

quickstep/src/com/android/launcher3/taskbar/NavbarButtonsViewController.java

@@ -714,6 +714,8 @@ public class NavbarButtonsViewController implements TaskbarControllers.LoggableT
      * setup wizard, or normal 3 button nav.
      */
     private void updateButtonLayoutSpacing() {
+        boolean isThreeButtonNav = mContext.isThreeButtonNav();
+
         DeviceProfile dp = mContext.getDeviceProfile();
         Resources res = mContext.getResources();
         boolean isInSetup = !mContext.isUserSetupComplete();
@@ -721,7 +723,9 @@ public class NavbarButtonsViewController implements TaskbarControllers.LoggableT
         boolean isInKidsMode = mContext.isNavBarKidsModeActive();
 
         if (TaskbarManager.FLAG_HIDE_NAVBAR_WINDOW) {
-            boolean isThreeButtonNav = mContext.isThreeButtonNav();
+            if (!isThreeButtonNav) {
+                return;
+            }
 
             NavButtonLayoutter navButtonLayoutter =
                     NavButtonLayoutFactory.Companion.getUiLayoutter(
@@ -803,7 +807,7 @@ public class NavbarButtonsViewController implements TaskbarControllers.LoggableT
             mNavButtonContainer.requestLayout();
 
             mHomeButton.setOnLongClickListener(null);
-        } else if (mContext.isThreeButtonNav()) {
+        } else if (isThreeButtonNav) {
             final RotateDrawable rotateDrawable = new RotateDrawable();
             rotateDrawable.setDrawable(mContext.getDrawable(R.drawable.ic_sysbar_back));
             rotateDrawable.setFromDegrees(0f);