WebLeakDetector: Fix false positive leaks on worker tests when oilpan is enabled.

Source/web/WebLeakDetector.cpp

 /*
  * Copyright (C) 2014 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 43 matching lines @@
 // Please see comment in Heap::collectAllGarbage()
 static const int kNumberOfGCsToClaimChains = 5;
 
 class WebLeakDetectorImpl FINAL : public WebLeakDetector {
 WTF_MAKE_NONCOPYABLE(WebLeakDetectorImpl);
 public:
     explicit WebLeakDetectorImpl(WebLeakDetectorClient* client)
         : m_client(client)
         , m_delayedGCAndReportTimer(this, &WebLeakDetectorImpl::delayedGCAndReport)
         , m_delayedReportTimer(this, &WebLeakDetectorImpl::delayedReport)
+        , m_numberOfGCNeeded(0)

[tkent, 2014/06/27 00:10:55]

We can initialize it with 2.

[tkent, 2014/06/27 00:11:56]

maybe no.  We may call collectGarbageAndGetDOMCounts multiple times for one
instance.

     {
         ASSERT(m_client);
     }
 
     virtual ~WebLeakDetectorImpl() { }
 
     virtual void collectGarbageAndGetDOMCounts(WebLocalFrame*) OVERRIDE;
 
 private:
     void delayedGCAndReport(Timer<WebLeakDetectorImpl>*);
     void delayedReport(Timer<WebLeakDetectorImpl>*);
 
     WebLeakDetectorClient* m_client;
     Timer<WebLeakDetectorImpl> m_delayedGCAndReportTimer;
     Timer<WebLeakDetectorImpl> m_delayedReportTimer;
+    int m_numberOfGCNeeded;
 };
 
 void WebLeakDetectorImpl::collectGarbageAndGetDOMCounts(WebLocalFrame* frame)
 {
     memoryCache()->evictResources();
 
     {
         RefPtrWillBeRawPtr<Document> document = PassRefPtrWillBeRawPtr<Document>(frame->document());
         if (ResourceFetcher* fetcher = document->fetcher())
             fetcher->garbageCollectDocumentResources();
     }
 
     // FIXME: HTML5 Notification should be closed because notification affects the result of number of DOM objects.
 
     for (int i = 0; i < kNumberOfGCsToClaimChains; ++i)
         V8GCController::collectGarbage(v8::Isolate::GetCurrent());
     // Note: Oilpan precise GC is scheduled at the end of the event loop.
 
     // Task queue may contain delayed object destruction tasks.
     // This method is called from navigation hook inside FrameLoader,
     // so previous document is still held by the loader until the next event loop.
     // Complete all pending tasks before proceeding to gc.
+    m_numberOfGCNeeded = 2;
     m_delayedGCAndReportTimer.startOneShot(0, FROM_HERE);
 }
 
 void WebLeakDetectorImpl::delayedGCAndReport(Timer<WebLeakDetectorImpl>*)
 {
-    // We do a second GC here to address flakiness: Resource GC may have postponed clean-up tasks to next event loop.
+    // We do a second and third GC here to address flakiness
+    // The second GC is necessary as Resource GC may have postponed clean-up tasks to next event loop.
+    // The third GC is necessary for cleaning up Document after worker object died.
 
     for (int i = 0; i < kNumberOfGCsToClaimChains; ++i)
         V8GCController::collectGarbage(V8PerIsolateData::mainThreadIsolate());
     // Note: Oilpan precise GC is scheduled at the end of the event loop.
 
     // Inspect counters on the next event loop.
-    m_delayedReportTimer.startOneShot(0, FROM_HERE);
+    if (--m_numberOfGCNeeded)
+        m_delayedGCAndReportTimer.startOneShot(0, FROM_HERE);
+    else
+        m_delayedReportTimer.startOneShot(0, FROM_HERE);
 }
 
 void WebLeakDetectorImpl::delayedReport(Timer<WebLeakDetectorImpl>*)
 {
     ASSERT(m_client);
 
     WebLeakDetectorClient::Result result;
     result.numberOfLiveDocuments = InspectorCounters::counterValue(InspectorCounters::DocumentCounter);
     result.numberOfLiveNodes = InspectorCounters::counterValue(InspectorCounters::NodeCounter);
 
     m_client->onLeakDetectionComplete(result);
 }
 
 } // namespace
 
 WebLeakDetector* WebLeakDetector::create(WebLeakDetectorClient* client)
 {
     return new WebLeakDetectorImpl(client);
 }
 
 } // namespace blink