Avoid sending FirstScreenBroadcast if there is nothing to send.

Bug: 216389279
Test: manual
Change-Id: I1c30f02cbb287c25a140cb4801d6b66b07cec3a7
diff --git a/src/com/android/launcher3/model/FirstScreenBroadcast.java b/src/com/android/launcher3/model/FirstScreenBroadcast.java
index e391d37..5fac7cf 100644
--- a/src/com/android/launcher3/model/FirstScreenBroadcast.java
+++ b/src/com/android/launcher3/model/FirstScreenBroadcast.java
@@ -135,6 +135,13 @@
             printList(installerPackageName, "Widget item", widgetItems);
         }
 
+        if (folderItems.isEmpty()
+                && workspaceItems.isEmpty()
+                && hotseatItems.isEmpty()
+                && widgetItems.isEmpty()) {
+            // Avoid sending broadcast if there is nothing to send.
+            return;
+        }
         context.sendBroadcast(new Intent(ACTION_FIRST_SCREEN_ACTIVE_INSTALLS)
                 .setPackage(installerPackageName)
                 .putStringArrayListExtra(FOLDER_ITEM_EXTRA, new ArrayList<>(folderItems))