Override isValidFragment for ContactsPreferenceActivity

Bug: 10651470
Change-Id: If123e6859c1d93b6571d88935dbe53152d539d8b
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index 3ea1dcb..7bbdc60 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -217,7 +217,8 @@
         <activity
             android:name=".preference.ContactsPreferenceActivity"
             android:label="@string/activity_title_settings"
-            android:theme="@style/ContactsPreferencesTheme" />
+            android:theme="@style/ContactsPreferencesTheme"
+            android:exported="false"/>
 
         <!-- Used to filter contacts list by account -->
         <activity