Drop event should generate user gesture.

Source/core/page/DragController.cpp

 /*
  * Copyright (C) 2007, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Google Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 50 matching lines @@
 #include "core/page/DragState.h"
 #include "core/page/EventHandler.h"
 #include "core/page/Page.h"
 #include "core/frame/Settings.h"
 #include "core/rendering/HitTestRequest.h"
 #include "core/rendering/HitTestResult.h"
 #include "core/rendering/RenderImage.h"
 #include "core/rendering/RenderTheme.h"
 #include "core/rendering/RenderView.h"
 #include "platform/DragImage.h"
+#include "platform/UserGestureIndicator.h"
 #include "platform/geometry/FloatRect.h"
 #include "platform/graphics/Image.h"
 #include "platform/graphics/ImageOrientation.h"
 #include "platform/network/ResourceRequest.h"
 #include "platform/weborigin/SecurityOrigin.h"
 #include "wtf/CurrentTime.h"
 #include "wtf/OwnPtr.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/RefPtr.h"
 
@@ skipping 146 matching lines @@
     if (m_fileInputElementUnderMouse)
         m_fileInputElementUnderMouse->setCanReceiveDroppedFiles(false);
     m_fileInputElementUnderMouse = nullptr;
 }
 
 DragSession DragController::dragUpdated(DragData* dragData)
 {
     return dragEnteredOrUpdated(dragData);
 }
 
 bool DragController::performDrag(DragData* dragData)

[abarth-chromium, 2014/03/24 03:51:29]

Are you sure this can't be triggered by script?

[wjywbs, 2014/03/24 12:14:10]

I tried to use script to trigger this function and I added a log, but this
function wasn't run. I believe this is not the code path to dispatch drop event
in script:

var event = document.createEvent("HTMLEvents");
event.initEvent("drop",true,true);
document.getElementById("div1").dispatchEvent(event);

 {
     ASSERT(dragData);
+    UserGestureIndicator gesture(DefinitelyProcessingNewUserGesture);
+
     m_documentUnderMouse = m_page->mainFrame()->documentAtPoint(dragData->clientPosition());
     if ((m_dragDestinationAction & DragDestinationActionDHTML) && m_documentIsHandlingDrag) {
         RefPtr<LocalFrame> mainFrame = m_page->mainFrame();
         bool preventedDefault = false;
         if (mainFrame->view()) {
             // Sending an event can result in the destruction of the view and part.
             RefPtrWillBeRawPtr<Clipboard> clipboard = createDraggingClipboard(ClipboardReadable, dragData);
             clipboard->setSourceOperation(dragData->draggingSourceOperationMask());
             preventedDefault = mainFrame->eventHandler().performDragAndDrop(createMouseEvent(dragData), clipboard.get());
             clipboard->setAccessPolicy(ClipboardNumb); // Invalidate clipboard here for security
@@ skipping 708 matching lines @@
 #else
     return keyState & PlatformEvent::CtrlKey;
 #endif
 }
 
 void DragController::cleanupAfterSystemDrag()
 {
 }
 
 } // namespace WebCore