Chrome Version: all
OS: all

What steps will reproduce the problem?
(1) Add an extension API method that is restricted to a OS (via platform parameter in _api_features.json)
(2) Run browser test ExtensionApiTest.StubsApp from a different OS.

What is the expected result?
Test passes. 

What happens instead?
Test fails. The extension API definitions returned by chrome.test.getApiDefinitions() contain all APIs, including the restricted ones.