[Telemetry] Do not close tab connections if the tab is already gone.

tools/telemetry/telemetry/page/shared_page_state.py

Index: tools/telemetry/telemetry/page/shared_page_state.py
diff --git a/tools/telemetry/telemetry/page/shared_page_state.py b/tools/telemetry/telemetry/page/shared_page_state.py
index 0e564f8f8eac99a3b5eb2019556ba62a37bba81e..620e3731fd14f496b87940e8d20687645b9a8c11 100644
--- a/tools/telemetry/telemetry/page/shared_page_state.py
+++ b/tools/telemetry/telemetry/page/shared_page_state.py
@@ -84,7 +84,8 @@ class SharedPageState(shared_user_story_state.SharedUserStoryState):
   def DidRunUserStory(self, results):
     if self._finder_options.profiler:
       self._StopProfiling(results)
-    util.CloseConnections(self._current_tab)
+    if self._current_tab:
+      util.CloseConnections(self._current_tab)
     self._test.CleanUpAfterPage(self._current_page, self._current_tab)
     if self._current_page.credentials and self._did_login_for_current_page:
       self.browser.credentials.LoginNoLongerNeeded(
@@ -253,6 +254,7 @@ class SharedPageState(shared_user_story_state.SharedUserStoryState):
       self._ImplicitPageNavigation()
       self._test.RunPage(self._current_page, self._current_tab, results)
     except exceptions.Error:
+      self._current_tab = None
       if self._test.is_multi_tab_test:
         # Avoid trying to recover from an unknown multi-tab state.
         exception_formatter.PrintFormattedException(