Make hasPendingActivity return false after the associated browsing context is detached

third_party/WebKit/Source/bindings/core/v8/V8GCController.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 154 matching lines @@
     if (value->IsIndependent())
       return;
 
     v8::Local<v8::Object> wrapper = v8::Local<v8::Object>::New(
         m_isolate, v8::Persistent<v8::Object>::Cast(*value));
     DCHECK(V8DOMWrapper::hasInternalFieldsSet(wrapper));
 
     const WrapperTypeInfo* type = toWrapperTypeInfo(wrapper);
     if (type->isActiveScriptWrappable() &&
         toScriptWrappable(wrapper)->hasPendingActivity()) {
-      m_isolate->SetObjectGroupId(*value, liveRootId());
-      ++m_domObjectsWithPendingActivity;
+      // Enable hasPendingActivity only when the associated
+      // ExecutionContext is not yet detached. This is a work-around
+      // to avoid memory leaks caused by hasPendingActivity that keeps
+      // returning true forever. This will be okay in practice because
+      // the spec requires to stop almost all DOM activities when the
+      // associated browsing context is detached. However, the real
+      // problem is that some hasPendingActivity's are wrongly implemented
+      // and never return false.
+      // TODO(haraken): Implement correct lifetime using traceWrapper.
+      ExecutionContext* context =
+          toExecutionContext(wrapper->CreationContext());
+      if (context && !context->activeDOMObjectsAreStopped()) {
+        m_isolate->SetObjectGroupId(*value, liveRootId());
+        ++m_domObjectsWithPendingActivity;
+      }
     }
 
     if (classId == WrapperTypeInfo::NodeClassId) {
       DCHECK(V8Node::hasInstance(wrapper, m_isolate));
       Node* node = V8Node::toImpl(wrapper);
       if (node->hasEventListeners())
         addReferencesForNodeWithEventListeners(
             m_isolate, node, v8::Persistent<v8::Object>::Cast(*value));
       Node* root = V8GCController::opaqueRootForGC(m_isolate, node);
       m_isolate->SetObjectGroupId(
@@ skipping 295 matching lines @@
 
     if (classId != WrapperTypeInfo::NodeClassId &&
         classId != WrapperTypeInfo::ObjectClassId)
       return;
 
     v8::Local<v8::Object> wrapper = v8::Local<v8::Object>::New(
         m_isolate, v8::Persistent<v8::Object>::Cast(*value));
     ASSERT(V8DOMWrapper::hasInternalFieldsSet(wrapper));
     // The ExecutionContext check is heavy, so it should be done at the last.
     if (toWrapperTypeInfo(wrapper)->isActiveScriptWrappable() &&
-        toScriptWrappable(wrapper)->hasPendingActivity()
-        // TODO(haraken): Currently we don't have a way to get a creation
-        // context from a wrapper. We should implement the way and enable
-        // the following condition.
-        //
-        // This condition affects only compositor workers, where one isolate
-        // is shared by multiple workers. If we don't have the condition,
-        // a worker object for a compositor worker doesn't get collected
-        // until all compositor workers in the same isolate lose pending
-        // activities. In other words, not having the condition delays
-        // destruction of a worker object of a compositor worker.
-        //
-        /* && toExecutionContext(wrapper->creationContext()) == m_executionContext */
-        )
-      m_pendingActivityFound = true;
+        toScriptWrappable(wrapper)->hasPendingActivity()) {
+      // See the comment in MajorGCWrapperVisitor::VisitPersistentHandle.
+      ExecutionContext* context =
+          toExecutionContext(wrapper->CreationContext());
+      if (context == m_executionContext && context &&
+          !context->activeDOMObjectsAreStopped())
+        m_pendingActivityFound = true;
+    }
   }
 
   bool pendingActivityFound() const { return m_pendingActivityFound; }
 
  private:
   v8::Isolate* m_isolate;
   Persistent<ExecutionContext> m_executionContext;
   bool m_pendingActivityFound;
 };
 
@@ skipping 10 matching lines @@
   double startTime = WTF::currentTimeMS();
   v8::HandleScope scope(isolate);
   PendingActivityVisitor visitor(isolate, executionContext);
   toIsolate(executionContext)->VisitHandlesWithClassIds(&visitor);
   scanPendingActivityHistogram.count(
       static_cast<int>(WTF::currentTimeMS() - startTime));
   return visitor.pendingActivityFound();
 }
 
 }  // namespace blink