Docserver: Factor SamplesModel out of SamplesDataSource

chrome/common/extensions/docs/server2/template_renderer.py

 # Copyright 2013 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.
 
 from data_source_registry import CreateDataSources
 from third_party.handlebar import Handlebar
 from url_constants import GITHUB_BASE, EXTENSIONS_SAMPLES
 
 
 class TemplateRenderer(object):
   '''Renders templates with the server's available data sources.
   '''
 
   def __init__(self, server_instance):
     self._server_instance = server_instance
 
   def Render(self,
              template,
              request,
              data_sources=None,
-             additional_context=None):
+             additional_context={}):
     '''Renders |template| using |request|.
 
     Specify |data_sources| to only include the DataSources with the given names
     when rendering the template.
 
     Specify |additional_context| to inject additional template context when
     rendering the template.
     '''
     assert isinstance(template, Handlebar), type(template)
-    render_context = self._CreateDataSources(request)
+    render_context = CreateDataSources(self._server_instance, request)
     if data_sources is not None:
       render_context = dict((name, d) for name, d in render_context.iteritems()
                             if name in data_sources)
     render_context.update({
       'apps_samples_url': GITHUB_BASE,
       'base_path': self._server_instance.base_path,
       'extensions_samples_url': EXTENSIONS_SAMPLES,
       'static': self._server_instance.base_path + 'static',
     })
-    if additional_context:
-      render_context.update(additional_context)
+    render_context.update(additional_context)
     render_data = template.Render(render_context)
     return render_data.text, render_data.errors
-
-  def _CreateDataSources(self, request):
-    server_instance = self._server_instance
-    data_sources = CreateDataSources(server_instance, request=request)
-    data_sources.update({
-      'samples': server_instance.samples_data_source_factory.Create(request),
-    })
-    return data_sources