Relative component names for dream settings activities.

If no package name is provided when declaring a dream settings
activity, use the dream service component package name.

Bug:8370189
Change-Id: I36fabc4e7f10fe7deb5bd7a670c66b2c23d5fc20

src/com/android/settings/DreamBackend.java

@@ -277,6 +277,9 @@ public class DreamBackend {
             Log.w(TAG, "Error parsing : " + resolveInfo.serviceInfo.packageName, caughtException);
             return null;
         }
+        if (cn != null && cn.indexOf('/') < 0) {
+            cn = resolveInfo.serviceInfo.packageName + "/" + cn;
+        }
         return cn == null ? null : ComponentName.unflattenFromString(cn);
     }