[FIX] core: content tab discovery in headful mode

It's not clear when and how this happened but apparently "headful"
chrome has a built-in background_page for hangouts which appears
before the `about:blank` page in the list of targets, and possibly
appears before the `about:blank` page has opened at all.

odoo/odoo#111422 was tested with chromium which apparently doesn't
have this feature either (or does it?), which probably contributes to
having no idea when it appears.

This feature also doesn't respond to `--disable-extensions`, despite
its url marking it as one:

    chrome-extension://nkeimhogjdpnpccoofpliimaahmaaome/background.html

The result was that the tour runner would hook onto the hangouts
target and try to load pages, which it would reject with
`net::ERR_ABORTED`, hence the tours just getting stuck.

Fix by improving the heuristic to find a content page: look for a
target of type `page`, and with the url `about:blank`, rather than
just take whichever tab target is listed first. Requires modifying
`stop` as it can now be called after we've started the browser, but
before we've created the websocket connection.

Also move `--no-first-run` from the headless to the default switches
to avoid Chrome's migration & default browser popup, apparently it
doesn't cause Chromium grief anymore (???). If this turns out to be a
concern, add a condition on the `executable` or something.

closes odoo/odoo#122117

Signed-off-by: Xavier Morel (xmo) <xmo@odoo.com>

odoo/tests/common.py

@@ -907,8 +907,7 @@ class ChromeBrowser:
             os._exit(0)
 
     def stop(self):
-        # only cleanup chrome if it was started before SIGXCPU triggered
-        if self.chrome:
+        if hasattr(self, 'ws'):
             self._websocket_send('Page.stopScreencast')
             if self.screencasts_dir and os.path.isdir(self.screencasts_frames_dir):
                 shutil.rmtree(self.screencasts_frames_dir)
@@ -928,6 +927,7 @@ class ChromeBrowser:
             self._websocket_send('Browser.close')
             self._logger.info("Closing websocket connection")
             self.ws.close()
+        if self.chrome:
             self._logger.info("Terminating chrome headless with pid %s", self.chrome.pid)
             self.chrome.terminate()
 
@@ -986,7 +986,6 @@ class ChromeBrowser:
             '--disable-dev-shm-usage': '',
             '--disable-namespace-sandbox': '',
             '--disable-translate': '',
-            '--no-first-run': '',
             '--no-sandbox': '',
             '--disable-gpu': '',
         }
@@ -1000,6 +999,7 @@ class ChromeBrowser:
             '--remote-debugging-port': str(self.remote_debugging_port),
             '--user-data-dir': user_data_dir,
             '--window-size': window_size,
+            '--no-first-run': '',
             # '--enable-precise-memory-info': '', # uncomment to debug memory leaks in qunit suite
             # '--js-flags': '--expose-gc', # uncomment to debug memory leaks in qunit suite
         }
@@ -1023,7 +1023,7 @@ class ChromeBrowser:
 
         return proc, devtools_port
 
-    def _json_command(self, command, timeout=3, get_key=None):
+    def _json_command(self, command, timeout=3):
         """Queries browser state using JSON
 
         Available commands:
@@ -1056,15 +1056,10 @@ class ChromeBrowser:
             except ProcessLookupError:
                 message = 'Chrome crashed at startup'
                 break
-            res = None
             try:
                 r = requests.get(url, timeout=3)
                 if r.ok:
-                    res = r.json()
-                    if get_key is None:
-                        return res
-                    else:
-                        return res[get_key]
+                    return r.json()
             except requests.ConnectionError as e:
                 failure_info = str(e)
                 message = 'Connection Error while trying to connect to Chrome debugger'
@@ -1072,8 +1067,7 @@ class ChromeBrowser:
                 failure_info = str(e)
                 message = 'Connection Timeout while trying to connect to Chrome debugger'
                 break
-            except (KeyError, IndexError):
-                message = 'Key "%s" not found in json result "%s" after connecting to Chrome debugger' % (get_key, res)
+
             time.sleep(delay)
             timeout -= delay
             delay = delay * 1.5
@@ -1087,8 +1081,23 @@ class ChromeBrowser:
     def _open_websocket(self):
         version = self._json_command('version')
         self._logger.info('Browser version: %s', version['Browser'])
-        infos = self._json_command('', get_key=0)  # Infos about the first tab
-        ws_url = infos['webSocketDebuggerUrl']
+
+        start = time.time()
+        while (time.time() - start) < 5.0:
+            ws_url = next((
+                target['webSocketDebuggerUrl']
+                for target in self._json_command('')
+                if target['type'] == 'page'
+                if target['url'] == 'about:blank'
+            ), None)
+            if ws_url:
+                break
+
+            time.sleep(0.1)
+        else:
+            self.stop()
+            raise unittest.SkipTest("Error during Chrome connection: never found 'page' target")
+
         self._logger.info('Websocket url found: %s', ws_url)
         ws = websocket.create_connection(ws_url, enable_multithread=True, suppress_origin=True)
         if ws.getstatus() != 101: