Make Platform::queryStorageUsageAndQuota work from worker threads

content/child/quota_message_filter.h

Index: content/child/quota_message_filter.h
diff --git a/content/child/quota_message_filter.h b/content/child/quota_message_filter.h
new file mode 100644
index 0000000000000000000000000000000000000000..5e90c6ccc83a1a61930010ea31d5a07e600d7d22
--- /dev/null
+++ b/content/child/quota_message_filter.h
@@ -0,0 +1,51 @@
+// Copyright 2013 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 CONTENT_CHILD_QUOTA_MESSAGE_FILTER_H_
+#define CONTENT_CHILD_QUOTA_MESSAGE_FILTER_H_
+
+#include <map>
+
+#include "base/synchronization/lock.h"
+#include "ipc/ipc_channel_proxy.h"
+
+namespace base {
+class MessageLoopProxy;
+}
+
+namespace content {
+
+class ThreadSafeSender;
+
+class QuotaMessageFilter : public IPC::ChannelProxy::MessageFilter {
+ public:
+  explicit QuotaMessageFilter(ThreadSafeSender* thread_safe_sender);
+
+  // IPC::Listener implementation.
+  virtual bool OnMessageReceived(const IPC::Message& msg) OVERRIDE;
+
+  // Registers { request_id, thread_id } map to the message filter.
+  // This method can be called on any thread.
+  void RegisterRequestID(int request_id, int thread_id);
+
+ protected:
+  virtual ~QuotaMessageFilter();
+
+ private:
+  typedef std::map<int, int> RequestIdToThreadId;
+
+  void DispatchMessage(const IPC::Message& msg);
+
+  scoped_refptr<base::MessageLoopProxy> main_thread_loop_proxy_;
+  scoped_refptr<ThreadSafeSender> thread_safe_sender_;
+
+  base::Lock request_id_map_lock_;
+  RequestIdToThreadId request_id_map_;
+
+  DISALLOW_COPY_AND_ASSIGN(QuotaMessageFilter);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_CHILD_QUOTA_MESSAGE_FILTER_H_