android.intent.action.CONTENT_CHANGED should be system protected

b/28795013

Change-Id: Id224b4169b7e0e27dc66f18576e95107a99f3866
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index 36d5ef6..a2d0bda 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -25,6 +25,8 @@
     <uses-permission android:name="android.permission.INTERACT_ACROSS_USERS_FULL" />
 
     <protected-broadcast android:name="android.provider.action.EXTERNAL_PROVIDER_CHANGE" />
+    <protected-broadcast android:name="android.intent.action.CONTENT_CHANGED" />
+
     <!-- This permission is only used to send the ACTION_EXTERNAL_PROVIDER_CHANGE intent. -->
     <uses-permission android:name="android.permission.MODIFY_PHONE_STATE" />