Fix update_policies.py

I think update_policies.py broke after
https://chromium-review.googlesource.com/657402, which changed the
contents of a group's policy list to be a list of strings, rather than a
list of policies.

Change-Id: I2f1e8ff415ebadf8c2dd44bcb476a0cce7600cf6
Bug: None
Reviewed-on: https://chromium-review.googlesource.com/747634Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Commit-Queue: Adam Langley <agl@chromium.org>
Cr-Commit-Position: refs/heads/master@{#512937}

tools/metrics/histograms/update_policies.py

@@ -36,22 +36,6 @@ class UserError(Exception):
     return self.args[0]
 
 
-def FlattenPolicies(policy_definitions, policy_list):
-  """Appends a list of policies defined in |policy_definitions| to
-  |policy_list|, flattening subgroups.
-
-  Args:
-    policy_definitions: A list of policy definitions and groups, as in
-                        policy_templates.json file.
-    policy_list: A list that has policy definitions appended to it.
-  """
-  for policy in policy_definitions:
-    if policy['type'] == 'group':
-      FlattenPolicies(policy['policies'], policy_list)
-    else:
-      policy_list.append(policy)
-
-
 def UpdateHistogramDefinitions(policy_templates, doc):
   """Sets the children of <enum name="EnterprisePolicies" ...> node in |doc| to
   values generated from policy ids contained in |policy_templates|.
@@ -80,8 +64,8 @@ def UpdateHistogramDefinitions(policy_templates, doc):
   policy_enum_node.appendChild(doc.createComment(comment))
 
   # Add values generated from policy templates.
-  ordered_policies = []
-  FlattenPolicies(policy_templates['policy_definitions'], ordered_policies)
+  ordered_policies = [x for x in policy_templates['policy_definitions']
+                      if x['type'] != 'group']
   ordered_policies.sort(key=lambda policy: policy['id'])
   for policy in ordered_policies:
     node = doc.createElement('int')