https://bugs.webkit.org/show_bug.cgi?id=126935
<rdar://problem/15790448>.

Reviewed by Timothy Horton.

Boiler plate code for getting the load policy logic from WebProcess to the UIProcess.

* UIProcess/API/C/WKAPICast.h:
(WebKit::toWebGLLoadPolicy):
* UIProcess/API/C/WKPageLoaderClient.h: Define a new WKPageLoaderClientV4 struct.
* UIProcess/API/Cocoa/WKBrowsingContextController.mm:
(setUpPageLoaderClient):
* UIProcess/WebLoaderClient.cpp:
(WebKit::WebLoaderClient::webGLLoadPolicy):
* UIProcess/WebLoaderClient.h:
* UIProcess/WebPageProxy.cpp:
(WebKit::WebPageProxy::webGLPolicyForURL):
* UIProcess/WebPageProxy.h:
* UIProcess/WebPageProxy.messages.in:
* WebProcess/WebCoreSupport/WebFrameLoaderClient.cpp:
(WebKit::WebFrameLoaderClient::webGLPolicyForURL): 
* WebProcess/WebCoreSupport/WebFrameLoaderClient.h:
* WebProcess/WebPage/WebPage.cpp:
(WebKit::WebPage::webGLPolicyForURL): We use a sendSync to get the load policy value from the UIProcess.
* WebProcess/WebPage/WebPage.h:
* WebKitTestRunner/TestController.cpp: Update WKPageLoaderClient to V4.
(WTR::TestController::createWebViewWithOptions):

Rename webGLPolicyForSite to webGLPolicyForURL.

* html/HTMLCanvasElement.cpp:
(WebCore::HTMLCanvasElement::getContext):
* loader/FrameLoaderClient.h:
(WebCore::FrameLoaderClient::webGLPolicyForURL):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@162141 268f45cc-cd09-0410-ab3c-d52691b4dbfc