Messaging: Fix loader not auto-restarting

When suspending and resuming the app, somehow the loader returns
immediately after onResume() with onLoadFinished() but somehow has no
data left (data.moveToNext() returns false) which makes the conversation
close immediately.
Restarting the loader has the desired result: We can leave the app
temporarily and come back to the same conversation again

This also fixes adding a vcard attachment (since that temporarily
leaves the app)

Change-Id: Id52e55563a11474fa776323477aa900ca4be0bbe

src/com/android/messaging/ui/conversation/ConversationFragment.java

@@ -678,6 +678,10 @@ public class ConversationFragment extends Fragment implements ConversationDataLi
         mComposeMessageView.saveInputState(outState);
     }
 
+    public void onRestart() {
+        mBinding.getData().restart(mBinding);
+    }
+
     @Override
     public void onResume() {
         super.onResume();