[IMP] tests: delete session cookie after each test

During an HttpCase, when a browser_js test is finished, cookies are
removed to ensure that the next call will start on a clean base.  From
time to times, when an HttpCase have multiple tests methods that call
browser_js, the user session of the previous test is being used.

With this commit, the session cookie is explicitely deleted and should
prevent that kind of problem. By the way, the browser's cache is also
cleared.

odoo/tests/common.py

@@ -776,6 +776,12 @@ class ChromeBrowser():
         _id = self._websocket_send('Network.setCookie', params=params)
         return self._websocket_wait_id(_id)
 
+    def delete_cookie(self, name, **kwargs):
+        params = {kw:kwargs[kw] for kw in kwargs if kw in ['url', 'domain', 'path']}
+        params.update({'name': name})
+        _id = self._websocket_send('Network.deleteCookies', params=params)
+        return self._websocket_wait_id(_id) 
+
     def _wait_ready(self, ready_code, timeout=60):
         self._logger.info('Evaluate ready code "%s"', ready_code)
         awaited_result = {'result': {'type': 'boolean', 'value': True}}
@@ -872,6 +878,8 @@ class ChromeBrowser():
         self.screencast_frames = []
         self._websocket_send('Page.stopLoading')
         self._logger.info('Deleting cookies and clearing local storage')
+        dc_id = self._websocket_send('Network.clearBrowserCache')
+        self._websocket_wait_id(dc_id)
         dc_id = self._websocket_send('Network.clearBrowserCookies')
         self._websocket_wait_id(dc_id)
         cl_id = self._websocket_send('Runtime.evaluate', params={'expression': 'localStorage.clear()'})
@@ -1037,6 +1045,7 @@ class HttpCase(TransactionCase):
         finally:
             # clear browser to make it stop sending requests, in case we call
             # the method several times in a test method
+            self.browser.delete_cookie('session_id', domain=HOST)
             self.browser.clear()
             self._wait_remaining_requests()