Initial notification blocker

Does not currently track stats across reboots.

Test: make ExtServicesUnitTests &&
adb install -r $OUT/data/app/ExtServicesUnitTests/ExtServicesUnitTests.apk &&
adb shell am instrument -w android.ext.services.tests.unit/android.support.test.runner.AndroidJUnitRunner
Bug: 63095540

Change-Id: Ie3a299cdfb229dedf85a07de5cc19f7a8ea423e0
diff --git a/packages/ExtServices/AndroidManifest.xml b/packages/ExtServices/AndroidManifest.xml
index f54b6fb..291009e 100644
--- a/packages/ExtServices/AndroidManifest.xml
+++ b/packages/ExtServices/AndroidManifest.xml
@@ -42,6 +42,15 @@
             </intent-filter>
         </service>
 
+        <service android:name=".notification.Assistant"
+                 android:label="@string/notification_assistant"
+                 android:permission="android.permission.BIND_NOTIFICATION_ASSISTANT_SERVICE"
+                 android:exported="true">
+            <intent-filter>
+                <action android:name="android.service.notification.NotificationAssistantService" />
+            </intent-filter>
+        </service>
+
         <library android:name="android.ext.services"/>
     </application>