Summary:
This only works for the new cxx bridge (hopefully open sourcing soon!).
This diff allows Java native modules to expose synchronous hooks to JS via the ReactSyncHook annotation. The methods will appear in JS on the native module object (e.g. you would do `require('UIManager').mySyncHook('foo');`) which allows us to enforce that required native modules are installed at build time. In order to support remote debugging, both the args and return type must be JSON serializable (so that we can go back across to the device to resolve synchronous hooks).
Follow ups will be integration tests, adding support for return types besides void, and adding support for remote debugging.
Reviewed By: mhorowitz
Differential Revision: D3218794
fb-gh-sync-id: 7e3366a8254276f5a55eb806287419287ca9182b
fbshipit-source-id: 7e3366a8254276f5a55eb806287419287ca9182b
50d8d46733