Add 1st cut of FileSystemUsageTracker that tracks the usage changes in FileSystem API.

webkit/fileapi/file_system_usage_tracker.h

Index: webkit/fileapi/file_system_usage_tracker.h
diff --git a/webkit/fileapi/file_system_usage_tracker.h b/webkit/fileapi/file_system_usage_tracker.h
new file mode 100644
index 0000000000000000000000000000000000000000..c6e4bfdcfab4264f452dfd8a286d894f20b200ca
--- /dev/null
+++ b/webkit/fileapi/file_system_usage_tracker.h
@@ -0,0 +1,67 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef WEBKIT_FILEAPI_FILE_SYSTEM_USAGE_TRACKER_H_
+#define WEBKIT_FILEAPI_FILE_SYSTEM_USAGE_TRACKER_H_
+
+#include <deque>
+#include <list>
+#include <map>
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/callback.h"
+#include "base/file_path.h"
+#include "base/ref_counted.h"
+#include "webkit/fileapi/file_system_types.h"
+
+class GURL;
+
+namespace base {
+class MessageLoopProxy;
+}
+
+namespace fileapi {
+
+class FileSystemUsageTracker {
+ public:
+  FileSystemUsageTracker(
+      scoped_refptr<base::MessageLoopProxy> file_message_loop,
+      const FilePath& profile_path,
+      bool is_incognito);
+  ~FileSystemUsageTracker();
+
+  // Get the amount of data stored in the filesystem specified by
+  // |origin_url| and |type|.
+  typedef Callback1<int64 /* usage */>::Type GetUsageCallback;
+  void GetOriginUsage(const GURL& origin_url,
+                      fileapi::FileSystemType type,
+                      GetUsageCallback* callback);
+
+ private:
+  class GetUsageTask;
+  friend class GetUsageTask;
+
+  void RegisterUsageTask(GetUsageTask* task);
+  void UnregisterUsageTask(GetUsageTask* task);
+
+  void DidGetOriginUsage(const std::string& fs_name, int64 usage);
+
+  scoped_refptr<base::MessageLoopProxy> file_message_loop_;
+  FilePath base_path_;
+  bool is_incognito_;
+
+  typedef std::deque<GetUsageTask*> UsageTaskQueue;
+  UsageTaskQueue running_usage_tasks_;
+
+  typedef std::list<GetUsageCallback*> PendingCallbackList;
+  typedef std::map<std::string, PendingCallbackList> PendingUsageCallbackMap;
+  PendingUsageCallbackMap pending_usage_callbacks_;
+
+  DISALLOW_COPY_AND_ASSIGN(FileSystemUsageTracker);
+};
+
+}  // namespace fileapi
+
+#endif  // WEBKIT_FILEAPI_FILE_SYSTEM_USAGE_TRACKER_H_