Merge 102405 - Source/WebCore: Improve handling of frame removal during requestAnimationFrame cal...

Source/WebCore/dom/ScriptedAnimationController.cpp

 /*
  * Copyright (C) 2011 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:
  * 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 43 matching lines @@
     , m_animationTimer(this, &ScriptedAnimationController::animationTimerFired)
     , m_lastAnimationFrameTime(0)
 #if USE(REQUEST_ANIMATION_FRAME_DISPLAY_MONITOR)
     , m_useTimer(false)
 #endif
 #endif
 {
     windowScreenDidChange(displayID);
 }
 
+ScriptedAnimationController::~ScriptedAnimationController()
+{
+}
+
 void ScriptedAnimationController::suspend()
 {
     ++m_suspendCount;
 }
 
 void ScriptedAnimationController::resume()
 {
     --m_suspendCount;
     if (!m_suspendCount && m_callbacks.size())
         scheduleAnimation();
@@ skipping 38 matching lines @@
     // FIXME: Currently, this code doesn't do any visibility tests beyond checking display:
 
     // First, generate a list of callbacks to consider.  Callbacks registered from this point
     // on are considered only for the "next" frame, not this one.
     CallbackList callbacks(m_callbacks);
 
     // Firing the callback may cause the visibility of other elements to change.  To avoid
     // missing any callbacks, we keep iterating through the list of candiate callbacks and firing
     // them until nothing new becomes visible.
     bool firedCallback;
+
+    // Invoking callbacks may detach elements from our document, which clear's the document's
+    // reference to us, so take a defensive reference.
+    RefPtr<ScriptedAnimationController> protector(this);
     do {
         firedCallback = false;
+        // A previous iteration may have detached this Document from the DOM tree.
+        // If so, then we do not need to process any more callbacks.
+        if (!m_document)
+            continue;
+
         // A previous iteration may have invalidated style (or layout).  Update styles for each iteration
         // for now since all we check is the existence of a renderer.
         m_document->updateStyleIfNeeded();
         for (size_t i = 0; i < callbacks.size(); ++i) {
             RequestAnimationFrameCallback* callback = callbacks[i].get();
             if (!callback->m_firedOrCancelled && (!callback->m_element || callback->m_element->renderer())) {
                 callback->m_firedOrCancelled = true;
                 InspectorInstrumentationCookie cookie = InspectorInstrumentation::willFireAnimationFrameEvent(m_document, callback->m_id);
                 callback->handleEvent(time);
                 InspectorInstrumentation::didFireAnimationFrameEvent(cookie);
@@ skipping 20 matching lines @@
 {
 #if USE(REQUEST_ANIMATION_FRAME_DISPLAY_MONITOR)
     DisplayRefreshMonitorManager::sharedManager()->windowScreenDidChange(displayID, this);
 #else
     UNUSED_PARAM(displayID);
 #endif    
 }
 
 void ScriptedAnimationController::scheduleAnimation()
 {
+    if (!m_document)
+        return;
+
 #if USE(REQUEST_ANIMATION_FRAME_TIMER)
 #if USE(REQUEST_ANIMATION_FRAME_DISPLAY_MONITOR)
     if (!m_useTimer) {
         if (DisplayRefreshMonitorManager::sharedManager()->scheduleAnimation(this))
             return;
             
         m_useTimer = true;
     }
 #endif
     if (m_animationTimer.isActive())
@@ skipping 12 matching lines @@
 {
     m_lastAnimationFrameTime = currentTime();
     serviceScriptedAnimations(convertSecondsToDOMTimeStamp(m_lastAnimationFrameTime));
 }
 #endif
 
 }
 
 #endif