sandwich: Fixes two sources of KeyError task failures

tools/android/loading/sandwich_utils.py

 # Copyright 2016 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 re
+import urlparse
+
 import common_util
 import emulation
 import sandwich_runner
 import task_manager
 
 
+class SandwichKnownError(Exception):
+  pass
+
+
+def NormalizeUrl(url):
+  """Returns normalized URL with trailing slashes."""
+  parsed_url = list(urlparse.urlparse(url))
+  parsed_url[2] = re.sub(r"/{2,}", r"/", parsed_url[2])
+  return urlparse.urlunparse(parsed_url)
+
+
 def NetworkSimulationTransformer(network_condition):
   """Creates a function that accepts a SandwichRunner as a parameter and sets
   network emulation options on it.
 
   Args:
     network_condition: The network condition to apply to the sandwich runner.
 
   Returns:
     A callback transforming the SandwichRunner given in argument accordingly
   """
@@ skipping 38 matching lines @@
     @self.RegisterTask('common/webpages.wpr')
     def BuildOriginalWpr():
       common_util.EnsureParentDirectoryExists(BuildOriginalWpr.path)
       runner = self.CreateSandwichRunner()
       runner.wpr_archive_path = BuildOriginalWpr.path
       runner.wpr_record = True
       runner.output_dir = BuildOriginalWpr.path[:-4] + '-run'
       runner.Run()
 
     self.original_wpr_task = BuildOriginalWpr