Clear FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS for dreams

By default, dreams should not get the in-window bars
because those conflict with the lights-out bar mode.

Bug: 17367264
Change-Id: I8c041c706f7a7c4791ed4760c34a5618fb7423d7

core/java/android/service/dreams/DreamService.java

@@ -967,6 +967,9 @@ public class DreamService extends Service implements Window.Callback {
                         | (mScreenBright ? WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON : 0)
                         );
             mWindow.setAttributes(lp);
+            // Workaround: Currently low-profile and in-window system bar backgrounds don't go
+            // along well. Dreams usually don't need such bars anyways, so disable them by default.
+            mWindow.clearFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
             mWindow.setWindowManager(null, windowToken, "dream", true);
 
             applySystemUiVisibilityFlags(