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// Copyright (c) 2012 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_GEOLOCATION_GEOLOCATION_PROVIDER_H_
#define CONTENT_BROWSER_GEOLOCATION_GEOLOCATION_PROVIDER_H_
#include <map>
#include <vector>
#include "base/basictypes.h"
#include "base/compiler_specific.h"
#include "base/threading/thread.h"
#include "content/browser/geolocation/geolocation_observer.h"
#include "content/common/content_export.h"
#include "content/public/browser/geolocation.h"
#include "content/public/common/geoposition.h"
class GeolocationArbitrator;
class GeolocationProviderTest;
template<typename Type> struct DefaultSingletonTraits;
// This is the main API to the geolocation subsystem. The application will hold
// a single instance of this class and can register multiple clients to be
// notified of location changes:
// * Observers are registered by AddObserver() and will keep receiving updates
// until unregistered by RemoveObserver().
// * Callbacks are registered by RequestCallback() and will be called exactly
// once when the next update becomes available.
// The application must instantiate the GeolocationProvider on the IO thread and
// must communicate with it on the same thread.
// The underlying location arbitrator will only be enabled whilst there is at
// least one registered observer or pending callback. The arbitrator and the
// location providers it uses run on a separate Geolocation thread.
class CONTENT_EXPORT GeolocationProvider
: public base::Thread, public GeolocationObserver {
public:
// The GeolocationObserverOptions passed are used as a 'hint' for the provider
// preferences for this particular observer, however the observer could
// receive updates for best available locations from any active provider
// whilst it is registered.
// If an existing observer is added a second time, its options are updated
// but only a single call to RemoveObserver() is required to remove it.
void AddObserver(GeolocationObserver* delegate,
const GeolocationObserverOptions& update_options);
// Remove a previously registered observer. No-op if not previously registered
// via AddObserver(). Returns true if the observer was removed.
bool RemoveObserver(GeolocationObserver* delegate);
// Request a single callback when the next location update becomes available.
// Callbacks must only be requested by code that is allowed to access the
// location. No further permission checks will be made.
void RequestCallback(const content::GeolocationUpdateCallback& callback);
void OnPermissionGranted();
bool HasPermissionBeenGranted() const;
// GeolocationObserver implementation.
virtual void OnLocationUpdate(const content::Geoposition& position) OVERRIDE;
// Overrides the location for automation/testing. Suppresses any further
// updates from the actual providers and sends an update with the overridden
// position to all registered clients.
void OverrideLocationForTesting(
const content::Geoposition& override_position);
// Gets a pointer to the singleton instance of the location relayer, which
// is in turn bound to the browser's global context objects. This must only be
// called on the IO thread so that the GeolocationProvider is always
// instantiated on the same thread. Ownership is NOT returned.
static GeolocationProvider* GetInstance();
protected:
friend struct DefaultSingletonTraits<GeolocationProvider>;
GeolocationProvider();
virtual ~GeolocationProvider();
private:
typedef std::map<GeolocationObserver*, GeolocationObserverOptions>
ObserverMap;
typedef std::vector<content::GeolocationUpdateCallback> CallbackList;
bool OnGeolocationThread() const;
// Start and stop providers as needed when clients are added or removed.
void OnClientsChanged();
// Stops the providers when there are no more registered clients. Note that
// once the Geolocation thread is started, it will stay alive (but sitting
// idle without any pending messages).
void StopProviders();
// Starts the geolocation providers or updates their options (delegates to
// arbitrator).
void StartProviders(const GeolocationObserverOptions& options);
// Updates the providers on the geolocation thread, which must be running.
void InformProvidersPermissionGranted();
// Notifies all registered clients that a position update is available.
void NotifyClients(const content::Geoposition& position);
// Thread
virtual void Init() OVERRIDE;
virtual void CleanUp() OVERRIDE;
// Only used on the IO thread
ObserverMap observers_;
CallbackList callbacks_;
bool is_permission_granted_;
content::Geoposition position_;
// True only in testing, where we want to use a custom position.
bool ignore_location_updates_;
// Only to be used on the geolocation thread.
GeolocationArbitrator* arbitrator_;
DISALLOW_COPY_AND_ASSIGN(GeolocationProvider);
};
#endif // CONTENT_BROWSER_GEOLOCATION_GEOLOCATION_PROVIDER_H_
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