Fix NPE when NetworkRequest is null.

Bug: 22293472
Change-Id: Ib43f7e1d27fff39b4437d8407a428f80feef7ae7
diff --git a/src/com/android/phone/vvm/omtp/sync/OmtpVvmSyncService.java b/src/com/android/phone/vvm/omtp/sync/OmtpVvmSyncService.java
index d0c6231..cce936b 100644
--- a/src/com/android/phone/vvm/omtp/sync/OmtpVvmSyncService.java
+++ b/src/com/android/phone/vvm/omtp/sync/OmtpVvmSyncService.java
@@ -200,7 +200,6 @@
                 downloadSuccess = true;
 
                 ImapHelper imapHelper = new ImapHelper(mContext, mPhoneAccount, network);
-
                 if (!imapHelper.isSuccessfullyInitialized()) {
                     Log.w(TAG, "Can't retrieve Imap credentials.");
                     releaseNetwork(this);
@@ -274,8 +273,10 @@
 
     private void requestNetwork(NetworkCallback networkCallback) {
         NetworkRequest networkRequest = mNetworkRequestMap.get(networkCallback);
-        getConnectivityManager().requestNetwork(
-                networkRequest, networkCallback, NETWORK_REQUEST_TIMEOUT_MILLIS);
+        if (networkRequest != null) {
+            getConnectivityManager().requestNetwork(
+                    networkRequest, networkCallback, NETWORK_REQUEST_TIMEOUT_MILLIS);
+        }
     }
 
     private void releaseNetwork(NetworkCallback networkCallback) {