Download LaTeX source code from Google Drive, strip it to plain text without comments, and compile. Just set the Google Doc sharing mode to "Anyone with the link", and paste the unique part of that link into the appropriate place in gen.sh

dehtml.py

import lxml.html
import sys

doc = lxml.html.fromstring(sys.stdin.read())

for elt in doc.cssselect('a, div, style, title'):
    elt.getparent().remove(elt)

s = u'\n'.join((elt.text_content() for elt in doc.cssselect('p, h1, h2, h3, h4, h5, h6'))) # add other nodes if I forgot any

tr = [
    (u'\u2018', "`"),
    (u'\u2019', "'"),
    (u'\u201c', "``"),
    (u'\u201d', "''"),
    (u'\xa0', ' '), # no-break space
]
for a, b in tr:
    s = s.replace(a, b)
sys.stdout.write(s.encode('latin1'))

gen.sh

#!/bin/bash
set -e
function get() {
	curl "https://docs.google.com/document/d/$2/export?format=html" | python dehtml.py > "$1".tex
}
NAME=paper
get $NAME      THE_LINK_CODE
#get intro      ANOTHER_CODE
#get results    ANOTHER_CODE
get ending     ANOTHER_CODE

pdflatex $NAME
bibtex $NAME
pdflatex $NAME
pdflatex $NAME

It would be quite easy to do this with a single Python script also.