Android: moves content/ to use long for JNI.

BUG=317523

Review URL: https://codereview.chromium.org/59673007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235815 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 235815