chromium/extensions/browser/api/system_info/system_info_provider.h

// Copyright 2013 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef EXTENSIONS_BROWSER_API_SYSTEM_INFO_SYSTEM_INFO_PROVIDER_H_
#define EXTENSIONS_BROWSER_API_SYSTEM_INFO_SYSTEM_INFO_PROVIDER_H_

#include "base/containers/queue.h"
#include "base/functional/bind.h"
#include "base/functional/callback.h"
#include "base/memory/ref_counted.h"

namespace base {
class SequencedTaskRunner;
}

namespace storage_monitor {
class StorageInfo;
}

namespace extensions {

namespace api {
namespace system_storage {
struct StorageUnitInfo;
}  // namespace system_storage
}  // namespace api

namespace systeminfo {

// Build StorageUnitInfo struct from StorageInfo instance. The |unit|
// parameter is the output value.
void BuildStorageUnitInfo(const storage_monitor::StorageInfo& info,
                          api::system_storage::StorageUnitInfo* unit);

}  // namespace systeminfo

// An abstract base class for all kinds of system information providers. Each
// kind of SystemInfoProvider is a single shared instance. It is created if
// needed, and destroyed at exit time. This is done via LazyInstance and
// scoped_refptr.
//
// The SystemInfoProvider is designed to query system information on the worker
// pool. It also maintains a queue of callbacks on the UI thread which are
// waiting for the completion of querying operation. Once the query operation
// is completed, all pending callbacks in the queue get called on the UI
// thread. In this way, it avoids frequent querying operation in case of lots
// of query requests, e.g. calling systemInfo.cpu.get repeatedly in an
// extension process.
//
// Each kind of SystemInfoProvider should satisfy an API query in a subclass on
// the blocking pool.
class SystemInfoProvider
    : public base::RefCountedThreadSafe<SystemInfoProvider> { … };

}  // namespace extensions

#endif  // EXTENSIONS_BROWSER_API_SYSTEM_INFO_SYSTEM_INFO_PROVIDER_H_