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// 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_BROWSER_DEVICE_ORIENTATION_DEVICE_MOTION_SERVICE_H_
#define CONTENT_BROWSER_DEVICE_ORIENTATION_DEVICE_MOTION_SERVICE_H_
#include "base/basictypes.h"
#include "base/callback_forward.h"
#include "base/memory/scoped_ptr.h"
#include "base/memory/shared_memory.h"
#include "base/memory/singleton.h"
#include "base/threading/thread_checker.h"
#include "content/common/content_export.h"
namespace content {
class DataFetcherSharedMemory;
class DeviceMotionProvider;
class RenderProcessHost;
// Owns the DeviceMotionProvider (the background polling thread) and keeps
// track of the number of consumers currently using the data (and pausing
// the provider when not in use).
class CONTENT_EXPORT DeviceMotionService {
public:
// Returns the DeviceMotionService singleton.
static DeviceMotionService* GetInstance();
// Increments the number of users of the provider. The Provider is running
// when there's > 0 users, and is paused when the count drops to 0.
//
// Must be called on the I/O thread.
void AddConsumer();
// Removes a consumer. Should be matched with an AddConsumer call.
//
// Must be called on the I/O thread.
void RemoveConsumer();
// Returns the shared memory handle of the device motion data duplicated
// into the given process.
base::SharedMemoryHandle GetSharedMemoryHandleForProcess(
base::ProcessHandle handle);
// Stop/join with the background thread in DeviceMotionProvider |provider_|.
void Shutdown();
private:
friend struct DefaultSingletonTraits<DeviceMotionService>;
DeviceMotionService();
virtual ~DeviceMotionService();
int num_readers_;
bool is_shutdown_;
scoped_ptr<DeviceMotionProvider> provider_;
base::ThreadChecker thread_checker_;
DISALLOW_COPY_AND_ASSIGN(DeviceMotionService);
};
} // namespace content
#endif // CONTENT_BROWSER_DEVICE_ORIENTATION_DEVICE_MOTION_SERVICE_H_
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