Add appProperty to ReactRootView

[maicki]

To get on par with iOS this PR adds an appProperty to the ReactRootView. The documentation on the iOS side is here: https://facebook.github.io/react-native/docs/communication-ios.html#properties.

You can pass in initial props with the startReactApplication method:

…
Bundle initialProps = new Bundle();

bundle.putString(“initialKey”, “initialValue”);
mReactRootView.startReactApplication(mReactInstanceManager, "HelloWorld", initialProps);
setContentView(mReactRootView);
…

And later on properties can be updated this way:

…
// Update props
Bundle updatedProps = mReactRootView.getAppProperties();

updatedProps.putString(“someOtherKey”, “someOtherValue”);

mReactRootView.setAppProperties(updatedProps);

// Replace props
Bundle newProps = new Bundle();

newProps.putString(“someKey”, “someValue”);

mReactRootView.setAppProperties(newProps);
…

The behavior on the JavaScript side should be the same as on iOS. The component of this root view will get a componentWillReceiveProps call with the new nextProps.

componentWillReceiveProps(nextProps) {
  // Will be called after calling setAppProperties
  console.log(nextProps);
}

There are a couple of open questions on my side though:

• Does it make sense to add runApplication method to RCTRootView? This is to not having to duplicate the code that injects the props in the react instance manager as well as in the root view.
• Do you see any problems renaming getLaunchOptions to getAppProperties to align the terminology with iOS?
• In setAppProperties what invariants needs to be tested so it’s safe to inject the new props (calling runApplication)?
• Any other architectural changes that could be done with this change?
• What test would be good to have ?

Would appreciate any feedback who is more involved with the Android architecture.

Adresses: #6303

cc @bestander @brentvatne

[javache]

nit: no need for this here

[javache]

Why do you need to pass in reactInstanceManager if it's already available as mReactInstanceManager?

[javache]

To avoid inconsistencies, let's assert that this method is UIThread only as well? (UiThreadUtil.assertOnUiThread())

[javache]

Add import on top for Argument instead

[javache]

Thanks for making this consistent with iOS! Maybe @AaaChiuuu can help review some of the finer details here?

[maicki]

@javache Thanks for looking into it! Addressed your comments.

[facebook-github-bot]

@javache has imported this pull request. If you are a Facebook employee, you can view this diff on Phabricator.

[maicki]

@javache Hey! Just want to follow up and ask what are best next steps to get this PR a bit further? Should I rebase, etc? Thanks!

[javache]

Hey @maicki, I'm running some internal tests on this currently, it should land sometime this week.

[meilers]

Any updates on this?

[maicki]

Hey @meilers, this change should have landed with 0.45: https://github.com/facebook/react-native/releases/tag/v0.45.1