Use default send_file max-age consistently.

Prior to this commit, the send_file max-age hook and config were only
used for the static file handler. Now they are used when calling
helpers.send_file directly.

flask/testsuite/blueprints.py

@@ -386,6 +386,29 @@ class BlueprintTestCase(FlaskTestCase):
         with flask.Flask(__name__).test_request_context():
             self.assert_equal(flask.render_template('nested/nested.txt'), 'I\'m nested')
 
+    def test_default_static_cache_timeout(self):
+        app = flask.Flask(__name__)
+        class MyBlueprint(flask.Blueprint):
+            def get_send_file_max_age(self, filename):
+                return 100
+
+        blueprint = MyBlueprint('blueprint', __name__, static_folder='static')
+        app.register_blueprint(blueprint)
+
+        # try/finally, in case other tests use this app for Blueprint tests.
+        max_age_default = app.config['SEND_FILE_MAX_AGE_DEFAULT']
+        try:
+            with app.test_request_context():
+                unexpected_max_age = 3600
+                if app.config['SEND_FILE_MAX_AGE_DEFAULT'] == unexpected_max_age:
+                    unexpected_max_age = 7200
+                app.config['SEND_FILE_MAX_AGE_DEFAULT'] = unexpected_max_age
+                rv = blueprint.send_static_file('index.html')
+                cc = parse_cache_control_header(rv.headers['Cache-Control'])
+                self.assert_equal(cc.max_age, 100)
+        finally:
+            app.config['SEND_FILE_MAX_AGE_DEFAULT'] = max_age_default
+
     def test_templates_list(self):
         from blueprintapp import app
         templates = sorted(app.jinja_env.list_templates())