Fix errors found with proguard

By default disable progaurd as enabling it will remove all java
classes marked as unused but they may be used by native. To enable
proguard need proguard.cfg file to have keep rules for Java
classes which are either used by native or dynamically called.

Change-Id: I54e990d9b829be54656a5904cb1427a2d2867234
diff --git a/AndroidManifest.xml.jinja2 b/AndroidManifest.xml.jinja2
index 3499f52..c349b8b 100644
--- a/AndroidManifest.xml.jinja2
+++ b/AndroidManifest.xml.jinja2
@@ -400,7 +400,7 @@
         </provider>
 
         <service
-            android:name=".UpdateNotificationService"
+            android:name="com.android.browser.UpdateNotificationService"
             android:exported="false" >
         </service>