Implement contextmenu attribute with basic support of <menu>

Source/core/page/ContextMenuController.cpp

Index: Source/core/page/ContextMenuController.cpp
diff --git a/Source/core/page/ContextMenuController.cpp b/Source/core/page/ContextMenuController.cpp
index 13680a5486f29ff9378e8ae7b4d748ff8590b81c..6b888f13afb3dc07a9e6ee5cbac8588c537c6ee3 100644
--- a/Source/core/page/ContextMenuController.cpp
+++ b/Source/core/page/ContextMenuController.cpp
@@ -28,18 +28,25 @@
 #include "core/page/ContextMenuController.h"
 
 #include "core/dom/Document.h"
+#include "core/dom/Node.h"
 #include "core/events/Event.h"
+#include "core/events/EventDispatchMediator.h"
+#include "core/events/EventDispatcher.h"
 #include "core/events/MouseEvent.h"
-#include "core/dom/Node.h"
+#include "core/events/RelatedEvent.h"
 #include "core/frame/LocalFrame.h"
+#include "core/html/HTMLMenuElement.h"
 #include "core/page/ContextMenuClient.h"
 #include "core/page/ContextMenuProvider.h"
+#include "core/page/CustomContextMenuProvider.h"
 #include "core/page/EventHandler.h"
 #include "platform/ContextMenu.h"
 #include "platform/ContextMenuItem.h"
 
 namespace blink {
 
+using namespace HTMLNames;
+
 ContextMenuController::ContextMenuController(Page*, ContextMenuClient* client)
     : m_client(client)
 {
@@ -79,12 +86,31 @@ void ContextMenuController::documentDetached(Document* document)
     }
 }
 
+void ContextMenuController::populateCustomContextMenu(Event* event)
+{
+    if (!RuntimeEnabledFeatures::contextMenuEnabled())
+        return;
+
+    Node* node = event->target()->toNode();
+    if (node && node->isHTMLElement()) {
+        HTMLElement& element = toHTMLElement(*node);
+        RefPtrWillBeRawPtr<HTMLMenuElement> menuElement = element.contextMenu();
+        RefPtrWillBeRawPtr<RelatedEvent> relatedEvent = RelatedEvent::create(EventTypeNames::show, true, true, node);
+        if (!menuElement->dispatchEvent(relatedEvent.release()))
+            return;
+        if (menuElement != element.contextMenu())
+            return;
+        m_menuProvider = CustomContextMenuProvider::create(*menuElement, element);
+        m_menuProvider->populateContextMenu(m_contextMenu.get());
+    }
+}
+
 void ContextMenuController::handleContextMenuEvent(Event* event)
 {
     m_contextMenu = createContextMenu(event);
     if (!m_contextMenu)
         return;
-
+    populateCustomContextMenu(event);
     showContextMenu(event);
 }