Gracefully handle failed task launches during quick switch

When quick switching from home or overview, go to OverviewState if the
task launch failed. Otherwise we get stuck in BackgroundAppState.

Bug: 135038270
Change-Id: I42785c261cef0df95666bc106ec5ca6ef0553cc7

quickstep/recents_ui_overrides/src/com/android/quickstep/FallbackActivityControllerHelper.java

@@ -224,4 +224,10 @@ public final class FallbackActivityControllerHelper implements
     public boolean isInLiveTileMode() {
         return false;
     }
+
+    @Override
+    public void onLaunchTaskFailed(RecentsActivity activity) {
+        // TODO: probably go back to overview instead.
+        activity.<RecentsView>getOverviewPanel().startHome();
+    }
 }