Fixing out of order taskbar callbacks

OnCreate can come before onDestroy for a previous activity which can
cause the callbacks for taskbar to get cleared

Bug: 190170303
Test: Presubmit
Change-Id: I48334605384d4604043a50ffc3d137f84575148a

quickstep/src/com/android/launcher3/BaseQuickstepLauncher.java

@@ -132,7 +132,7 @@ public abstract class BaseQuickstepLauncher extends Launcher
 
         unbindService(mTisBinderConnection);
         if (mTaskbarManager != null) {
-            mTaskbarManager.setLauncher(null);
+            mTaskbarManager.clearLauncher(this);
         }
         super.onDestroy();
     }