Oilpan: make shutdown of plugin container objects work better.

Source/web/WebPluginContainerImpl.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 285 matching lines @@
 
     // If either of the layers is null we need to switch between hardware
     // and software compositing.
     bool needsCompositingUpdate = !m_webLayer || !layer;
 
     m_webLayer = layer;
 
     if (!needsCompositingUpdate)
         return;
 
+#if ENABLE(OILPAN)
+    if (!m_element)
+        return;
+#endif
+
     m_element->setNeedsCompositingUpdate();
     // Being composited or not affects the self painting layer bit
     // on the RenderLayer.
     if (RenderPart* renderer = m_element->renderPart()) {
         ASSERT(renderer->hasLayer());
         renderer->layer()->updateSelfPaintingLayer();
     }
 }
 
 bool WebPluginContainerImpl::supportsPaginatedPrint() const
@@ skipping 103 matching lines @@
         m_scrollbarGroup->setFrameRect(frameRect());
     }
 }
 
 void WebPluginContainerImpl::allowScriptObjects()
 {
 }
 
 void WebPluginContainerImpl::clearScriptObjects()
 {
-    LocalFrame* frame = m_element->document().frame();
-    if (!frame)
+    if (!frame())
         return;
-    frame->script().cleanupScriptObjectsForPlugin(this);
+
+    frame()->script().cleanupScriptObjectsForPlugin(this);
 }
 
 NPObject* WebPluginContainerImpl::scriptableObjectForElement()
 {
     return m_element->getNPObject();
 }
 
 WebString WebPluginContainerImpl::executeScriptURL(const WebURL& url, bool popupsAllowed)
 {
     LocalFrame* frame = m_element->document().frame();
@@ skipping 203 matching lines @@
     context->setFillColor(Color(0xCC, 0xCC, 0xCC));
     context->fillRect(intersection(horizontalOverhangArea, dirtyRect));
     context->fillRect(intersection(verticalOverhangArea, dirtyRect));
     context->restore();
     return true;
 }
 
 // Private methods -------------------------------------------------------------
 
 WebPluginContainerImpl::WebPluginContainerImpl(WebCore::HTMLPlugInElement* element, WebPlugin* webPlugin)
-    : m_element(element)
+    : WebCore::FrameDestructionObserver(element->document().frame())
+    , m_element(element)
     , m_webPlugin(webPlugin)
     , m_webLayer(0)
     , m_touchEventRequestType(TouchEventRequestTypeNone)
     , m_wantsWheelEvents(false)
 {
 }
 
 WebPluginContainerImpl::~WebPluginContainerImpl()
 {
+#if ENABLE(OILPAN)
+    // The element (and its document) are heap allocated and may
+    // have been finalized by now; unsafe to unregister the touch
+    // event handler at this stage.
+    //
+    // This is acceptable, as the widget will unregister itself if it
+    // is cleanly detached. If an explicit detach doesn't happen, this
+    // container is assumed to have died with the plugin element (and
+    // its document), hence no unregistration step is needed.
+    //
+    m_element = 0;
+#else
     if (m_touchEventRequestType != TouchEventRequestTypeNone)
         m_element->document().didRemoveTouchEventHandler(m_element);
+#endif
 
     for (size_t i = 0; i < m_pluginLoadObservers.size(); ++i)
         m_pluginLoadObservers[i]->clearPluginContainer();
     m_webPlugin->destroy();
     if (m_webLayer)
         GraphicsLayer::unregisterContentsLayer(m_webLayer);
 }
 
+#if ENABLE(OILPAN)
+void WebPluginContainerImpl::detach()
+{
+    if (m_touchEventRequestType != TouchEventRequestTypeNone)
+        m_element->document().didRemoveTouchEventHandler(m_element);
+
+    setWebLayer(0);
+}
+#endif
+
 void WebPluginContainerImpl::handleMouseEvent(MouseEvent* event)
 {
     ASSERT(parent()->isFrameView());
 
     if (event->isDragEvent()) {
         if (m_webPlugin->canProcessDrag())
             handleDragEvent(event);
         return;
     }
 
@@ skipping 225 matching lines @@
 
     return clipRect;
 }
 
 bool WebPluginContainerImpl::pluginShouldPersist() const
 {
     return m_webPlugin->shouldPersist();
 }
 
 } // namespace blink