[chromium] Set the Helper Plugin's URL to that of the host document.
https://bugs.webkit.org/show_bug.cgi?id=111913

This allows content settings, etc. to be based on the document hosting
the element that requested the Helper Plugin.

Patch by David Dorwin <ddorwin@chromium.org> on 2013-03-09
Reviewed by Adam Barth.

* src/WebHelperPluginImpl.cpp:
(WebKit::writeDocument):
(WebKit::WebHelperPluginImpl::initialize):
(WebKit::WebHelperPluginImpl::initializePage):
* src/WebHelperPluginImpl.h:
(WebKit):
(WebHelperPluginImpl):
* src/WebMediaPlayerClientImpl.cpp:
(WebKit::WebMediaPlayerClientImpl::createHelperPlugin):
* src/WebViewImpl.cpp:
(WebKit::WebViewImpl::createHelperPlugin):
* src/WebViewImpl.h:
(WebViewImpl):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@145319 268f45cc-cd09-0410-ab3c-d52691b4dbfc