[Telemetry] Fix up desktop_browser_finder on Linux

tools/telemetry/telemetry/testing/system_stub.py

 # Copyright 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.
 
 """Provides stubs for os, sys and subprocess for testing
 
 This test allows one to test code that itself uses os, sys, and subprocess.
 """
 
 import os
@@ skipping 337 matching lines @@
 
     @staticmethod
     def expanduser(path):
       return os.path.expanduser(path)
 
     @staticmethod
     def dirname(path):
       return os.path.dirname(path)
 
     @staticmethod
+    def realpath(path):
+      return os.path.realpath(path)
+
+    @staticmethod
+    def split(path):
+      return os.path.split(path)
+
+    @staticmethod
     def splitext(path):
       return os.path.splitext(path)
 
     @staticmethod
     def splitdrive(path):
       return os.path.splitdrive(path)
 
   X_OK = os.X_OK
 
   sep = os.sep
@@ skipping 109 matching lines @@
       elif device_id == 'failure':
         raise Exception('Test exception.')
 
     def install_cert(self, overwrite_cert=False):
       pass
 
 class PlatformSettingsStub(object):
   @staticmethod
   def HasSniSupport():
     return True