Add ObjC API for setting initialization data for the WKWebProcessPlugIn
https://bugs.webkit.org/show_bug.cgi?id=103846

Reviewed by Darin Adler.

* UIProcess/API/mac/WKProcessGroup.h:
Adds a new optional processGroupWillCreateConnectionToWebProcessPlugIn: method for the WKProcessGroupDelegate protocol,
which allows the user to pass (via an autoreleased return value) initialization data to the web process plugin.

* UIProcess/API/mac/WKProcessGroup.mm:
(getInjectedBundleInitializationUserData):
(setUpInectedBundleClient):
(-[WKProcessGroup initWithInjectedBundleURL:]):
(-[WKProcessGroup dealloc]):
Use the existing WKContextInjectedBundleClient infrastructure to pass the initialization data to the bundle
via the new ObjCObjectGraph APIObject.

* WebProcess/InjectedBundle/API/mac/WKWebProcessPlugIn.h:
Adds webProcessPlugIn:initializeWithObject: to the WKWebProcessPlugIn protocol, replacing webProcessPlugInInitialize:.

* WebProcess/InjectedBundle/mac/InjectedBundleMac.mm:
(WebKit::InjectedBundle::load):
Pass the initialization data to the web process plugin.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@148376 268f45cc-cd09-0410-ab3c-d52691b4dbfc