Add resource locking in gclient

gclient.py

Index: gclient.py
diff --git a/gclient.py b/gclient.py
index 3569f8ebed154d6e4ddb54ac65393c7e5b6a6de8..aedcf8a5e43d7898316517bd42ed1de97ce8d722 100755
--- a/gclient.py
+++ b/gclient.py
@@ -375,6 +375,13 @@ class Dependency(gclient_utils.WorkItem, DependencySettings):
     # It will be a dictionary of {deps_name: {"deps_file": depfile_name}} or
     # None.
     self.recursedeps = None
+    # This is inherited from WorkItem.  We want the URL to be a resource.
+    if url:
+      # The url is usually given to gclient either as https://blah@123
+      # or just https://blah.  The @123 portion is irrelevent.
+      url_segments = url.split('@')
+      if url_segments > 0:

[Sergey Berezin, 2016/06/08 18:50:47]

nit: str.split('@') always returns a non-empty array, so this branch is
redundant.

However, url is not a str here - see presubmit failure.

+        self.resources.append(url_segments[0])
 
     if not self.name and self.parent:
       raise gclient_utils.Error('Dependency without name')