[NaCl SDK Docs] Only generate one top-level <section> element.

native_client_sdk/src/doc/_sphinxext/chromesite_builder.py

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 #
 # This is a Sphinx extension.
 #
 
 from __future__ import print_function
 import codecs
@@ skipping 85 matching lines @@
       # auto-generated navbar and permalinks.
       if node.parent.hasattr('ids'):
         node['ids'] = node.parent['ids'][:]
 
     HTMLTranslator.visit_title(self, node)
 
 
   def visit_section(self, node):
     # chromesite needs <section> instead of <div class='section'>
     self.section_level += 1
-    self.body.append(self.starttag(node, 'section'))
+    if self.section_level == 1:
+      self.body.append(self.starttag(node, 'section'))
 
   def depart_section(self, node):
+    if self.section_level == 1:
+      self.body.append('</section>')
     self.section_level -= 1
-    self.body.append('</section>')
 
   def visit_image(self, node):
     # Paths to images in .rst sources should be absolute. This visitor does the
     # required transformation for the path to be correct in the final HTML.
     # if self.builder.chromesite_production_mode:
     node['uri'] = self.builder.get_production_url(node['uri'])
     HTMLTranslator.visit_image(self, node)
 
   def visit_reference(self, node):
     # In "kill_internal_links" mode, we don't emit the actual links for internal
@@ skipping 174 matching lines @@
   from sphinx.builders import linkcheck
   import urllib2
   linkcheck.HeadRequest = urllib2.Request
 
   app.add_directive('naclcode', NaclCodeDirective)
   app.add_builder(ChromesiteBuilder)
 
   # "Production mode" for local testing vs. on-server documentation.
   app.add_config_value('chromesite_kill_internal_links', default='0',
                        rebuild='html')