remove use of {,un}setPendingActivity from DOMFileSystem.

Source/modules/filesystem/DOMFileSystem.cpp

 /*
  * Copyright (C) 2010 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 70 matching lines @@
     rootURL.append("/");
     rootURL.append(filesystemId);
     rootURL.append("/");
 
     return DOMFileSystem::create(context, filesystemName.toString(), FileSystemTypeIsolated, KURL(ParsedURLString, rootURL.toString()));
 }
 
 DOMFileSystem::DOMFileSystem(ExecutionContext* context, const String& name, FileSystemType type, const KURL& rootURL)
     : DOMFileSystemBase(context, name, type, rootURL)
     , ActiveDOMObject(context)
+    , m_numberOfPendingCallbacks(0)
 {
     ScriptWrappable::init(this);
 }
 
 PassRefPtrWillBeRawPtr<DirectoryEntry> DOMFileSystem::root()
 {
     return DirectoryEntry::create(this, DOMFilePath::root);
 }
 
 void DOMFileSystem::addPendingCallbacks()
 {
-    setPendingActivity(this);
+    ++m_numberOfPendingCallbacks;
 }
 
 void DOMFileSystem::removePendingCallbacks()
 {
-    unsetPendingActivity(this);
+    ASSERT(m_numberOfPendingCallbacks > 0);
+    --m_numberOfPendingCallbacks;
+}
+
+bool DOMFileSystem::hasPendingActivity() const
+{
+    ASSERT(m_numberOfPendingCallbacks >= 0);
+    return m_numberOfPendingCallbacks;
 }
 
 void DOMFileSystem::reportError(PassOwnPtr<ErrorCallback> errorCallback, PassRefPtrWillBeRawPtr<FileError> fileError)
 {
     scheduleCallback(errorCallback, fileError);
 }
 
 namespace {
 
 class ConvertToFileWriterCallback : public FileWriterBaseCallback {
@@ skipping 79 matching lines @@
 
 } // namespace
 
 void DOMFileSystem::createFile(const FileEntry* fileEntry, PassOwnPtr<FileCallback> successCallback, PassOwnPtr<ErrorCallback> errorCallback)
 {
     KURL fileSystemURL = createFileSystemURL(fileEntry);
     fileSystem()->createSnapshotFileAndReadMetadata(fileSystemURL, SnapshotFileCallback::create(this, fileEntry->name(), fileSystemURL, successCallback, errorCallback));
 }
 
 } // namespace WebCore