Add gclient hook to download prebuilt mojo_shell

tools/find_depot_tools.py

 # Copyright (c) 2011 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.
 """Small utility function to find depot_tools and add it to the python path.
 
 Will throw an ImportError exception if depot_tools can't be found since it
 imports breakpad.
 """
 
 import os
 import sys
 
 
 def IsRealDepotTools(path):
-  return os.path.isfile(os.path.join(path, 'gclient'))
+  return os.path.isfile(os.path.join(path, 'gclient.py'))
 
 
 def add_depot_tools_to_path():
   """Search for depot_tools and add it to sys.path."""
   # First look if depot_tools is already in PYTHONPATH.
   for i in sys.path:
-    if i.rstrip(os.sep).endswith('depot_tools') and IsRealDepotTools(i):
-      return i
+    if i.rstrip(os.sep).endswith('depot_tools'):
+      if IsRealDepotTools(i):
+        return i

[abarth-chromium, 2014/10/21 21:24:29]

Why this change?

[jamesr, 2014/10/21 22:10:15]

Lingering effects of diagnostic changes - will revert

   # Then look if depot_tools is in PATH, common case.
   for i in os.environ['PATH'].split(os.pathsep):
     if IsRealDepotTools(i):
       sys.path.append(i.rstrip(os.sep))
       return i
   # Rare case, it's not even in PATH, look upward up to root.
   root_dir = os.path.dirname(os.path.abspath(__file__))
   previous_dir = os.path.abspath(__file__)
   while root_dir and root_dir != previous_dir:
     i = os.path.join(root_dir, 'depot_tools')
     if IsRealDepotTools(i):
       sys.path.append(i)
       return i
     previous_dir = root_dir
     root_dir = os.path.dirname(root_dir)
   print >> sys.stderr, 'Failed to find depot_tools'
   return None
 
 add_depot_tools_to_path()
 
 # pylint: disable=W0611
 import breakpad