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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_NETWORK_LOCATION_PROVIDER_H_
      6 #define CONTENT_BROWSER_GEOLOCATION_NETWORK_LOCATION_PROVIDER_H_
      7 
      8 #include <list>
      9 #include <map>
     10 
     11 #include "base/basictypes.h"
     12 #include "base/memory/ref_counted.h"
     13 #include "base/memory/scoped_ptr.h"
     14 #include "base/memory/weak_ptr.h"
     15 #include "base/strings/string16.h"
     16 #include "base/threading/non_thread_safe.h"
     17 #include "base/threading/thread.h"
     18 #include "content/browser/geolocation/location_provider_base.h"
     19 #include "content/browser/geolocation/network_location_request.h"
     20 #include "content/browser/geolocation/wifi_data_provider_manager.h"
     21 #include "content/common/content_export.h"
     22 #include "content/public/common/geoposition.h"
     23 
     24 namespace content {
     25 class AccessTokenStore;
     26 
     27 
     28 class NetworkLocationProvider
     29     : public base::NonThreadSafe,
     30       public LocationProviderBase {
     31  public:
     32   // Cache of recently resolved locations. Public for tests.
     33   class CONTENT_EXPORT PositionCache {
     34    public:
     35     // The maximum size of the cache of positions.
     36     static const size_t kMaximumSize;
     37 
     38     PositionCache();
     39     ~PositionCache();
     40 
     41     // Caches the current position response for the current set of cell ID and
     42     // WiFi data. In the case of the cache exceeding kMaximumSize this will
     43     // evict old entries in FIFO orderer of being added.
     44     // Returns true on success, false otherwise.
     45     bool CachePosition(const WifiData& wifi_data,
     46                        const Geoposition& position);
     47 
     48     // Searches for a cached position response for the current set of data.
     49     // Returns NULL if the position is not in the cache, or the cached
     50     // position if available. Ownership remains with the cache.
     51     const Geoposition* FindPosition(const WifiData& wifi_data);
     52 
     53    private:
     54     // Makes the key for the map of cached positions, using a set of
     55     // data. Returns true if a good key was generated, false otherwise.
     56     static bool MakeKey(const WifiData& wifi_data,
     57                         base::string16* key);
     58 
     59     // The cache of positions. This is stored as a map keyed on a string that
     60     // represents a set of data, and a list to provide
     61     // least-recently-added eviction.
     62     typedef std::map<base::string16, Geoposition> CacheMap;
     63     CacheMap cache_;
     64     typedef std::list<CacheMap::iterator> CacheAgeList;
     65     CacheAgeList cache_age_list_;  // Oldest first.
     66   };
     67 
     68   NetworkLocationProvider(AccessTokenStore* access_token_store,
     69                           net::URLRequestContextGetter* context,
     70                           const GURL& url,
     71                           const base::string16& access_token);
     72   virtual ~NetworkLocationProvider();
     73 
     74   // LocationProvider implementation
     75   virtual bool StartProvider(bool high_accuracy) OVERRIDE;
     76   virtual void StopProvider() OVERRIDE;
     77   virtual void GetPosition(Geoposition *position) OVERRIDE;
     78   virtual void RequestRefresh() OVERRIDE;
     79   virtual void OnPermissionGranted() OVERRIDE;
     80 
     81  private:
     82   // Satisfies a position request from cache or network.
     83   void RequestPosition();
     84 
     85   // Gets called when new wifi data is available.
     86   void OnWifiDataUpdate();
     87 
     88   // Internal helper used by OnWifiDataUpdate.
     89   void OnWifiDataUpdated();
     90 
     91   bool IsStarted() const;
     92 
     93   void OnLocationResponse(const Geoposition& position,
     94                           bool server_error,
     95                           const base::string16& access_token,
     96                           const WifiData& wifi_data);
     97 
     98   scoped_refptr<AccessTokenStore> access_token_store_;
     99 
    100   // The wifi data provider, acquired via global factories.
    101   WifiDataProviderManager* wifi_data_provider_manager_;
    102 
    103   WifiDataProviderManager::WifiDataUpdateCallback wifi_data_update_callback_;
    104 
    105   // The  wifi data and a flag to indicate if the data set is complete.
    106   WifiData wifi_data_;
    107   bool is_wifi_data_complete_;
    108 
    109   // The timestamp for the latest wifi data update.
    110   base::Time wifi_data_updated_timestamp_;
    111 
    112   // Cached value loaded from the token store or set by a previous server
    113   // response, and sent in each subsequent network request.
    114   base::string16 access_token_;
    115 
    116   // The current best position estimate.
    117   Geoposition position_;
    118 
    119   // Whether permission has been granted for the provider to operate.
    120   bool is_permission_granted_;
    121 
    122   bool is_new_data_available_;
    123 
    124   // The network location request object, and the url it uses.
    125   scoped_ptr<NetworkLocationRequest> request_;
    126 
    127   // The cache of positions.
    128   scoped_ptr<PositionCache> position_cache_;
    129 
    130   base::WeakPtrFactory<NetworkLocationProvider> weak_factory_;
    131 
    132   DISALLOW_COPY_AND_ASSIGN(NetworkLocationProvider);
    133 };
    134 
    135 // Factory functions for the various types of location provider to abstract
    136 // over the platform-dependent implementations.
    137 CONTENT_EXPORT LocationProviderBase* NewNetworkLocationProvider(
    138     AccessTokenStore* access_token_store,
    139     net::URLRequestContextGetter* context,
    140     const GURL& url,
    141     const base::string16& access_token);
    142 
    143 }  // namespace content
    144 
    145 #endif  // CONTENT_BROWSER_GEOLOCATION_NETWORK_LOCATION_PROVIDER_H_
    146