Add support for top level geolocation arbitrator, and access token persistenc...

chrome/browser/geolocation/location_arbitrator.h

+// 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_
+
+class AccessTokenStore;
+class URLRequestContextGetter;
+struct Position;
+
+// 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:
+  // Creates and returns a new instance of the location arbitrator.
+  static GeolocationArbitrator* New(AccessTokenStore* access_token_store,
+                                    URLRequestContextGetter* context_getter);
+
+  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 Position& position) = 0;
+
+   protected:
+    virtual ~Delegate() {}
+  };
+  struct UpdateOptions {
+    UpdateOptions() : use_high_accuracy(false) {}
+    bool use_high_accuracy;
+  };
+
+  virtual ~GeolocationArbitrator();
+
+  // 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()
+  virtual void 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.
+  virtual void SetUseMockProvider(bool use_mock) = 0;
+};
+
+#endif  // CHROME_BROWSER_GEOLOCATION_LOCATION_ARBITRATOR_H_