Support API aliases

chrome/common/extensions/api/_features.md

Index: chrome/common/extensions/api/_features.md
diff --git a/chrome/common/extensions/api/_features.md b/chrome/common/extensions/api/_features.md
index bd4a86ee1adf1b9d58d6015fd1388f860c6742a0..ebe6ac26421f1dad468f0233309a7e83d978a25f 100644
--- a/chrome/common/extensions/api/_features.md
+++ b/chrome/common/extensions/api/_features.md
@@ -119,6 +119,16 @@ feature.
 
 The following properties are supported in the feature system.
 
+### alias
+
+The `alias` property is available only for API features. It should be set for
+API features that have an alias. The value should be the name of the alias API

[Devlin, 2016/11/14 18:03:56]

We should describe what an alias is here. :)

[tbarzic, 2016/11/15 04:45:07]

Done.

+feature. The alias feature should have `source` property set to the name of the
+API that it aliased.
+
+For complex features, `alias` property will be set to the `alias` value of the
+first component simple feature that has it set.
+
 ### blacklist
 
 The `blacklist` property specifies a list of ID hashes for extensions that
@@ -265,6 +275,19 @@ use 'session_types' property will be disabled when a user is not logged in).
 
 The accepted values are lists of strings from `regular` and `kiosk`.
 
+### source

[Devlin, 2016/11/14 18:03:56]

I think having an example here would probably be useful.

[tbarzic, 2016/11/15 04:45:07]

Done.

+
+The `source` property is available only for API features. It should be set for
+alias API feature. The value should be the name of the API the alias is
+aliasing. The source API feature should have `alias` property set to the alias
+API name.
+The alias API will inherit schema from the source API, but it will not respect
+the source API child features. To accomplish parity with the source API feature
+children, identical child features should be added for the alias API.
+
+For complex features, `source` property will be set to the `source` value of the
+first component simple feature that has it set.
+
 ### whitelist
 
 The `whitelist` property specifies a list of ID hashes for extensions that