LibWeb: Added get source functionality and hook event

Author: https://github.com/xeons
Commit: 2f56a86a4e
Pull-request: https://github.com/SerenityOS/serenity/pull/5477
Reviewed-by: https://github.com/awesomekling

Userland/Libraries/LibWeb/OutOfProcessWebView.cpp

@@ -314,6 +314,12 @@ String OutOfProcessWebView::notify_server_did_request_prompt(Badge<WebContentCli
     return {};
 }
 
+void OutOfProcessWebView::notify_server_did_get_source(const URL& url, const String& source)
+{
+    if (on_get_source)
+        on_get_source(url, source);
+}
+
 void OutOfProcessWebView::did_scroll()
 {
     client().post_message(Messages::WebContentServer::SetViewportRect(visible_content_rect()));
@@ -340,4 +346,9 @@ void OutOfProcessWebView::debug_request(const String& request, const String& arg
     client().post_message(Messages::WebContentServer::DebugRequest(request, argument));
 }
 
+void OutOfProcessWebView::get_source()
+{
+    client().post_message(Messages::WebContentServer::GetSource());
+}
+
 }