[Telemetry] Fix tab list updating with connected tabs.

tools/telemetry/telemetry/tab_list_backend.py

 # Copyright (c) 2012 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.
 import httplib
 import json
 import socket
 import urllib2
 import weakref
 
 from telemetry import browser_gone_exception
@@ skipping 43 matching lines @@
 
     tab_id = debugger_url.split('/')[-1]
     try:
       response = self._browser_backend.Request('close/%s' % tab_id,
                                                timeout=timeout)
     except urllib2.HTTPError:
       raise Exception('Unable to close tab, tab id not found: %s' % tab_id)
     assert response == 'Target is closing'
 
     util.WaitFor(lambda: not self._FindTabInfo(debugger_url), timeout=5)
+
+    if debugger_url in self._tab_dict:
+      del self._tab_dict[debugger_url]
     self._UpdateTabList()
 
   def ActivateTab(self, debugger_url, timeout=None):
     assert self._browser_backend.supports_tab_control
 
     assert debugger_url in self._tab_dict
     tab_id = debugger_url.split('/')[-1]
     try:
       response = self._browser_backend.Request('activate/%s' % tab_id,
                                                timeout=timeout)
@@ skipping 52 matching lines @@
     except (socket.error, httplib.BadStatusLine, urllib2.URLError):
       if not self._browser_backend.IsBrowserRunning():
         raise browser_gone_exception.BrowserGoneException()
       raise BrowserConnectionGoneException()
 
   def _UpdateTabList(self):
     def GetDebuggerUrl(tab_info):
       if 'webSocketDebuggerUrl' not in tab_info:
         return None
       return tab_info['webSocketDebuggerUrl']
-    newtab_list = map(GetDebuggerUrl, self._ListTabs())
-    self._tab_list = [t for t in self._tab_list if t in newtab_list]
-    self._tab_list += [t for t in newtab_list if t not in self._tab_list]
+    new_tab_list = map(GetDebuggerUrl, self._ListTabs())
+    self._tab_list = [t for t in self._tab_list
+                      if t in self._tab_dict or t in new_tab_list]
+    self._tab_list += [t for t in new_tab_list
+                       if t is not None and t not in self._tab_list]
 
   def _FindTabInfo(self, debugger_url):
     for tab_info in self._ListTabs():
       if tab_info.get('webSocketDebuggerUrl') == debugger_url:
         return tab_info
     return None