Telemetry: Update exception handling in FastNavigationProfileExtender.

tools/perf/profile_creators/profile_extender.py

 # Copyright 2013 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.
 
 from telemetry.core import browser_finder
 from telemetry.core import browser_finder_exceptions
 from telemetry.core import platform
 from telemetry.core import wpr_modes
 
 
@@ skipping 69 matching lines @@
   def TearDownBrowser(self):
     """Tears down the browser.
 
     Can be overridden by subclasses. The subclass implementation must call the
     super class implementation.
     """
     if self._browser:
       self._browser.Close()
       self._browser = None
 
+  def VerifyProfileWasExtended(self):
+    """Verifies that the profile was correctly extended.
+
+    Can be overridden by subclasses.
+    """
+    pass
+
   def FetchWebPageReplayArchives(self):
     """Fetches the web page replay archives.
 
     Can be overridden by subclasses.
     """
     pass
 
   def _SetUpWebPageReplay(self, finder_options, possible_browser):
     """Sets up Web Page Replay, if necessary."""
 
@@ skipping 23 matching lines @@
     possible_browser = browser_finder.FindBrowser(finder_options)
     if not possible_browser:
       raise browser_finder_exceptions.BrowserFinderException(
           'No browser found.\n\nAvailable browsers:\n%s\n' %
           '\n'.join(browser_finder.GetAllAvailableBrowserTypes(finder_options)))
     finder_options.browser_options.browser_type = (
         possible_browser.browser_type)
 
     return possible_browser