Documented how to add bookmark folders with the ManagedBookmarks policy.

components/policy/resources/policy_templates.json

Index: components/policy/resources/policy_templates.json
diff --git a/components/policy/resources/policy_templates.json b/components/policy/resources/policy_templates.json
index f6583982040622748680848bae755fc7a7902dab..191c9156e21335dc138ed4588303291c916a70d6 100644
--- a/components/policy/resources/policy_templates.json
+++ b/components/policy/resources/policy_templates.json
@@ -6418,6 +6418,8 @@
 
       The policy is a list of bookmarks, and each bookmark is a dictionary containing the bookmark "name" and target "url".
 
+      A bookmark can also be configured as a folder. In that case, define the folder "name" but don't define an "url"; instead, define the folder contents as another list of bookmarks under the "children" key.

[bartfab (slow), 2014/08/28 13:21:17]

Nit: Is it possible to specify in JSON schema somehow that there can only be
either |url| or |children|?

[Joao da Silva, 2014/08/28 13:38:09]

It is but it's complicated :-)

Basically, the "type" field can map to a specific type (that's what we're using
all over the place) but it can also map to a list of types. In that case, the
value must match one of those types. This simple example would allow a string or
a boolean:

  "type": [ "string", "boolean" ]

Interestingly, instead of naming a type you can just inline another schema.

So the "type: object" line above could be broken into "type: [ { schema_for_urls
}, { schema_for_folders } ]"

Unfortunately the schema validator doesn't support this yet :-) It's nice that
JSON schema can express union types like this, but I'm not sure we will
implement it without a good reason for it.

+
       These bookmarks are placed in a Managed bookmarks folder inside the Mobile bookmarks. These bookmarks can't be modified by the user.
 
       When this policy is set then the Managed bookmarks are the default folder opened when the bookmarks view is opened in <ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph>.