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

webkit/fileapi/sandboxed_file_system_context.h

Index: webkit/fileapi/sandboxed_file_system_context.h
diff --git a/webkit/fileapi/sandboxed_file_system_context.h b/webkit/fileapi/sandboxed_file_system_context.h
index fcb90bb4fc2422b140e08bac9054127052be8499..e3b7a6740a599079f39efb38cb6c3cfc376c477a 100644
--- a/webkit/fileapi/sandboxed_file_system_context.h
+++ b/webkit/fileapi/sandboxed_file_system_context.h
@@ -19,6 +19,7 @@ namespace fileapi {
 
 class FileSystemPathManager;
 class FileSystemQuotaManager;
+class FileSystemUsageTracker;
 class SandboxedFileSystemContext;
 
 struct DefaultContextDeleter;
@@ -37,8 +38,6 @@ class SandboxedFileSystemContext
       bool unlimited_quota);
   ~SandboxedFileSystemContext();
 
-  void Shutdown();
-
   void DeleteDataForOriginOnFileThread(const GURL& origin_url);
 
   // Quota related methods.
@@ -47,16 +46,17 @@ class SandboxedFileSystemContext
 
   FileSystemPathManager* path_manager() { return path_manager_.get(); }
   FileSystemQuotaManager* quota_manager() { return quota_manager_.get(); }
+  FileSystemUsageTracker* usage_tracker() { return usage_tracker_.get(); }
 
  private:
   friend struct DefaultContextDeleter;
   void DeleteOnCorrectThread() const;
 
-  bool allow_file_access_from_files_;
   scoped_refptr<base::MessageLoopProxy> file_message_loop_;
   scoped_refptr<base::MessageLoopProxy> io_message_loop_;
   scoped_ptr<FileSystemPathManager> path_manager_;
   scoped_ptr<FileSystemQuotaManager> quota_manager_;
+  scoped_ptr<FileSystemUsageTracker> usage_tracker_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(SandboxedFileSystemContext);
 };