Remove the synchronization

All of the callbacks happen on the same thread; no need to
synchronize. Also move away from TimerTask and use Handler to post
the termination callback.

Change-Id: If684e29686f2c7557cc56057c7f1ec6a1dfd3bcb
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index cc095cf..42f544d 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -24,6 +24,10 @@
     <!-- TODO(gilad): Better understand/document this use case. -->
     <uses-permission android:name="android.permission.STOP_APP_SWITCHES" />
 
+    <!-- Declare which SDK level this application was built against. This is needed so that IDEs
+         can check for incompatible APIs. -->
+    <uses-sdk android:minSdkVersion="19" />
+
     <application android:persistent="false"
             android:label="@string/telecommAppLabel"
             android:icon="@mipmap/ic_launcher_phone"