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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CONTENT_BROWSER_GEOLOCATION_GEOLOCATION_PROVIDER_IMPL_H_
      6 #define CONTENT_BROWSER_GEOLOCATION_GEOLOCATION_PROVIDER_IMPL_H_
      7 
      8 #include <list>
      9 #include <vector>
     10 
     11 #include "base/basictypes.h"
     12 #include "base/callback_forward.h"
     13 #include "base/compiler_specific.h"
     14 #include "base/threading/thread.h"
     15 #include "content/common/content_export.h"
     16 #include "content/public/browser/geolocation_provider.h"
     17 #include "content/public/common/geoposition.h"
     18 
     19 template<typename Type> struct DefaultSingletonTraits;
     20 
     21 namespace content {
     22 class GeolocationArbitrator;
     23 class GeolocationProviderTest;
     24 
     25 // This is the main API to the geolocation subsystem. The application will hold
     26 // a single instance of this class and can register multiple clients to be
     27 // notified of location changes:
     28 // * Observers are registered by AddLocationUpdateCallback() and will keep
     29 //   receiving updates
     30 //   until unregistered by RemoveLocationUpdateCallback().
     31 // * Callbacks are registered by RequestCallback() and will be called exactly
     32 //   once when the next update becomes available.
     33 // The application must instantiate the GeolocationProvider on the IO thread and
     34 // must communicate with it on the same thread.
     35 // The underlying location arbitrator will only be enabled whilst there is at
     36 // least one registered observer or pending callback. The arbitrator and the
     37 // location providers it uses run on a separate Geolocation thread.
     38 class CONTENT_EXPORT GeolocationProviderImpl
     39     : public NON_EXPORTED_BASE(GeolocationProvider),
     40       public base::Thread {
     41  public:
     42   // GeolocationProvider implementation:
     43   virtual void AddLocationUpdateCallback(const LocationUpdateCallback& callback,
     44                                          bool use_high_accuracy) OVERRIDE;
     45   virtual bool RemoveLocationUpdateCallback(
     46       const LocationUpdateCallback& callback) OVERRIDE;
     47   virtual void UserDidOptIntoLocationServices() OVERRIDE;
     48 
     49   bool LocationServicesOptedIn() const;
     50 
     51   // Overrides the location for automation/testing. Suppresses any further
     52   // updates from the actual providers and sends an update with the overridden
     53   // position to all registered clients.
     54   void OverrideLocationForTesting(const Geoposition& override_position);
     55 
     56   // Callback from the GeolocationArbitrator. Public for testing.
     57   void OnLocationUpdate(const Geoposition& position);
     58 
     59   // Gets a pointer to the singleton instance of the location relayer, which
     60   // is in turn bound to the browser's global context objects. This must only be
     61   // called on the IO thread so that the GeolocationProviderImpl is always
     62   // instantiated on the same thread. Ownership is NOT returned.
     63   static GeolocationProviderImpl* GetInstance();
     64 
     65  protected:
     66   friend struct DefaultSingletonTraits<GeolocationProviderImpl>;
     67   GeolocationProviderImpl();
     68   virtual ~GeolocationProviderImpl();
     69 
     70   // Useful for injecting mock geolocation arbitrator in tests.
     71   virtual GeolocationArbitrator* CreateArbitrator();
     72 
     73  private:
     74   typedef std::pair<LocationUpdateCallback, bool> LocationUpdateInfo;
     75   typedef std::list<LocationUpdateInfo> CallbackList;
     76 
     77   bool OnGeolocationThread() const;
     78 
     79   // Start and stop providers as needed when clients are added or removed.
     80   void OnClientsChanged();
     81 
     82   // Stops the providers when there are no more registered clients. Note that
     83   // once the Geolocation thread is started, it will stay alive (but sitting
     84   // idle without any pending messages).
     85   void StopProviders();
     86 
     87   // Starts the geolocation providers or updates their options (delegates to
     88   // arbitrator).
     89   void StartProviders(bool use_high_accuracy);
     90 
     91   // Updates the providers on the geolocation thread, which must be running.
     92   void InformProvidersPermissionGranted();
     93 
     94   // Notifies all registered clients that a position update is available.
     95   void NotifyClients(const Geoposition& position);
     96 
     97   // Thread
     98   virtual void Init() OVERRIDE;
     99   virtual void CleanUp() OVERRIDE;
    100 
    101   // Only used on the IO thread
    102   CallbackList callbacks_;
    103   bool user_did_opt_into_location_services_;
    104   Geoposition position_;
    105 
    106   // True only in testing, where we want to use a custom position.
    107   bool ignore_location_updates_;
    108 
    109   // Only to be used on the geolocation thread.
    110   GeolocationArbitrator* arbitrator_;
    111 
    112   DISALLOW_COPY_AND_ASSIGN(GeolocationProviderImpl);
    113 };
    114 
    115 }  // namespace content
    116 
    117 #endif  // CONTENT_BROWSER_GEOLOCATION_GEOLOCATION_PROVIDER_IMPL_H_
    118