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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_GEOLOCATION_LOCATION_ARBITRATOR_H_
#define CHROME_BROWSER_GEOLOCATION_LOCATION_ARBITRATOR_H_
#include "base/ref_counted.h"
class AccessTokenStore;
class URLRequestContextGetter;
struct Geoposition;
// This is the main API to the geolocaiton subsystem. Typically the application
// will hold a single instance of this class, and can register multiple
// observers which will be notified of location updates. Underlying location
// provider(s) will only be enabled whilst there is at least one observer
// registered.
// This class is responsible for handling updates from multiple underlying
// providers and resolving them to a single 'best' location fix at any given
// moment.
class GeolocationArbitrator : public base::RefCounted<GeolocationArbitrator> {
public:
// Creates and returns a new instance of the location arbitrator. Allows
// injection of the access token store and url getter context, for testing.
static GeolocationArbitrator* Create(
AccessTokenStore* access_token_store,
URLRequestContextGetter* context_getter);
// Gets a pointer to the singleton instance of the location arbitrator, which
// is in turn bound to the browser's global context objects. Ownership is NOT
// returned.
static GeolocationArbitrator* GetInstance();
class Delegate {
public:
// This will be called whenever the 'best available' location is updated,
// or when an error is encountered meaning no location data will be
// available in the forseeable future.
virtual void OnLocationUpdate(const Geoposition& position) = 0;
protected:
virtual ~Delegate() {}
};
struct UpdateOptions {
UpdateOptions() : use_high_accuracy(false) {}
explicit UpdateOptions(bool high_accuracy)
: use_high_accuracy(high_accuracy) {}
bool use_high_accuracy;
};
// Must be called from the same thread as the arbitrator was created on.
// The update options passed are used as a 'hint' for the provider preferences
// for this particular observer, however the delegate could receive callbacks
// for best available locations from any active provider whilst it is
// registerd.
// If an existing delegate is added a second time it's options are updated
// but only a single call to RemoveObserver() is required to remove it.
virtual void AddObserver(Delegate* delegate,
const UpdateOptions& update_options) = 0;
// Remove a previously registered observer. No-op if not previously registered
// via AddObserver(). Returns true if the observer was removed.
virtual bool RemoveObserver(Delegate* delegate) = 0;
// TODO(joth): This is a stop-gap for testing; once we have decoupled
// provider factory we should extract mock creation from the arbitrator.
static void SetUseMockProvider(bool use_mock);
protected:
friend class base::RefCounted<GeolocationArbitrator>;
GeolocationArbitrator();
// RefCounted object; no not delete directly.
virtual ~GeolocationArbitrator();
private:
DISALLOW_COPY_AND_ASSIGN(GeolocationArbitrator);
};
#endif // CHROME_BROWSER_GEOLOCATION_LOCATION_ARBITRATOR_H_
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