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// Copyright (c) 2010 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 CHROME_BROWSER_DEVICE_ORIENTATION_PROVIDER_H_
#define CHROME_BROWSER_DEVICE_ORIENTATION_PROVIDER_H_
#include "base/logging.h"
#include "base/ref_counted.h"
namespace device_orientation {
class Orientation;
class Provider : public base::RefCounted<Provider> {
public:
class Observer {
public:
// Called when the orientation changes.
// An Observer must not synchronously call Provider::RemoveObserver
// or Provider::AddObserver when this is called.
virtual void OnOrientationUpdate(const Orientation& orientation) = 0;
};
// Returns a pointer to the singleton instance of this class.
// The caller should store the returned pointer in a scoped_refptr.
// The Provider instance is lazily constructed when GetInstance() is called,
// and destructed when the last scoped_refptr referring to it is destructed.
static Provider* GetInstance();
// Inject a mock Provider for testing. Only a weak pointer to the injected
// object will be held by Provider, i.e. it does not itself contribute to the
// injected object's reference count.
static void SetInstanceForTests(Provider* provider);
virtual void AddObserver(Observer* observer) {}
virtual void RemoveObserver(Observer* observer) {}
protected:
Provider() {}
virtual ~Provider() {
DCHECK(instance_ == this);
instance_ = NULL;
}
private:
friend class base::RefCounted<Provider>;
static Provider* instance_;
DISALLOW_COPY_AND_ASSIGN(Provider);
};
} // namespace device_orientation
#endif // CHROME_BROWSER_DEVICE_ORIENTATION_PROVIDER_H_
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