Really fix org.xwalk.core.internal.xwview.test.loadTest#testContentUrl.

The <provider> tag in AndroidManifest.xml should be outside <activity>,
not inside it.

Pointy hat: darktears, rakuco.

BUG=XWALK-2172
Merge pull request #2249 from rakuco/really-fix-xwalk-2172

Really fix org.xwalk.core.internal.xwview.test.loadTest#testContentUrl.