Restore fix for native activity without a java-code

The regression was introduced by 39bfee5e3674faea992c32204abc1c03429b8cda
which undid the fix to classloader construction.

This commit reapplies the fix from b9c9026bdd0076014aeca62b088053d8fbce2326

Bug: http://b/27250344
Change-Id: I6c341d911ba0f311c63e380dd9dd064ba2faf391
1 file changed