Make breakpad, gcl and presubmit_support dependencies optional

gclient_utils.py

 # Copyright 2009 Google Inc.  All Rights Reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
 #
 #      http://www.apache.org/licenses/LICENSE-2.0
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 17 matching lines @@
 class CheckCallError(OSError):
   """CheckCall() returned non-0."""
   def __init__(self, command, cwd, retcode, stdout):
     OSError.__init__(self, command, cwd, retcode, stdout)
     self.command = command
     self.cwd = cwd
     self.retcode = retcode
     self.stdout = stdout
 
 
-def CheckCall(command, cwd=None):
+def CheckCall(command, cwd=None, print_error=True):
   """Like subprocess.check_call() but returns stdout.
 
   Works on python 2.4
   """
   try:
+    stderr = None
+    if not print_error:
+      stderr = subprocess.PIPE
     process = subprocess.Popen(command, cwd=cwd,
                                shell=sys.platform.startswith('win'),
-                               stdout=subprocess.PIPE)
+                               stdout=subprocess.PIPE,
+                               stderr=stderr)
     output = process.communicate()[0]
   except OSError, e:
     raise CheckCallError(command, cwd, errno, None)
   if process.returncode:
     raise CheckCallError(command, cwd, process.returncode, output)
   return output
 
 
 def SplitUrlRevision(url):
   """Splits url and returns a two-tuple: url, rev"""
@@ skipping 239 matching lines @@
     raise Error(msg)
 
 
 def IsUsingGit(root, paths):
   """Returns True if we're using git to manage any of our checkouts.
   |entries| is a list of paths to check."""
   for path in paths:
     if os.path.exists(os.path.join(root, path, '.git')):
       return True
   return False