Summary: This adds a persistent cookie store that shares cookies with WebView.
Add a `ForwardingCookieHandler` to OkHttp that uses the underlying Android webkit `CookieManager`.
Use a `LazyCookieHandler` to defer initialization of `CookieManager` as this will in turn trigger initialization of the Chromium stack in KitKat+ which takes some time. This was we will incur this cost on a background network thread instead of during startup.
Also add a `clearCookies()` method to the network module.
Add a cookies example to the XHR example. This example should also work for iOS (except for the clear cookies part). They are for now just scoped to Android.
Closes#2792.
public
Reviewed By: andreicoman11
Differential Revision: D2615550
fb-gh-sync-id: ff726a35f0fc3c7124d2f755448fe24c9d1caf21