DozeService: Fix crash if StatusBar not yet initialized

Fixes a bug where a crashing SystemUI may crash again after restarting
if the services restart in an unexpected order.

Bug: 34044765
Test: Crash SystemUI, observe that it doesn't crash again right away.
Change-Id: Id6f781ba29ff11be0850b1883ca2942f15e76324

packages/SystemUI/src/com/android/systemui/doze/DozeFactory.java

@@ -152,7 +152,7 @@ public class DozeFactory {
         }
     }
 
-    private static DozeHost getHost(DozeService service) {
+    public static DozeHost getHost(DozeService service) {
         Application appCandidate = service.getApplication();
         final SystemUIApplication app = (SystemUIApplication) appCandidate;
         return app.getComponent(DozeHost.class);

packages/SystemUI/src/com/android/systemui/doze/DozeService.java

@@ -42,6 +42,11 @@ public class DozeService extends DreamService implements DozeMachine.Service {
 
         setWindowless(true);
 
+        if (DozeFactory.getHost(this) == null) {
+            finish();
+            return;
+        }
+
         DozeProvider provider = PluginManager.getInstance(this)
                 .getOneShotPlugin(DozeProvider.ACTION, DozeProvider.VERSION);
         mDozeMachine = new DozeFactory(provider).assembleMachine(this);
@@ -62,6 +67,8 @@ public class DozeService extends DreamService implements DozeMachine.Service {
 
     @Override
     protected void dumpOnHandler(FileDescriptor fd, PrintWriter pw, String[] args) {
-        mDozeMachine.dump(pw);
+        if (mDozeMachine != null) {
+            mDozeMachine.dump(pw);
+        }
     }
 }