Dispatch geolocation IPCs on the UI thread. Aside from simplifying the code to avoid a lot of threa…

content/browser/geolocation/geolocation_provider_impl.h

 // 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_IMPL_H_
 #define CONTENT_BROWSER_GEOLOCATION_GEOLOCATION_PROVIDER_IMPL_H_
 
 #include <list>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/callback_forward.h"
 #include "base/compiler_specific.h"
 #include "base/threading/thread.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/geolocation_provider.h"
 #include "content/public/common/geoposition.h"
 
 template<typename Type> struct DefaultSingletonTraits;
 
 namespace content {
 class LocationArbitrator;
 
-// 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:
-// * Callbacks are registered by AddLocationUpdateCallback() and will keep
-//   receiving updates until unregistered by RemoveLocationUpdateCallback().
-// 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 GeolocationProviderImpl
     : public NON_EXPORTED_BASE(GeolocationProvider),
       public base::Thread {
  public:
   // GeolocationProvider implementation:
-  virtual void AddLocationUpdateCallback(const LocationUpdateCallback& callback,
-                                         bool use_high_accuracy) OVERRIDE;
-  virtual bool RemoveLocationUpdateCallback(
-      const LocationUpdateCallback& callback) OVERRIDE;
+  virtual scoped_ptr<GeolocationProvider::Subscription>
+      AddLocationUpdateCallback(const LocationUpdateCallback& callback,
+                                bool use_high_accuracy) OVERRIDE;
   virtual void UserDidOptIntoLocationServices() OVERRIDE;
-
-  bool LocationServicesOptedIn() const;
-
-  // 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 Geoposition& override_position);
+  virtual void OverrideLocationForTesting(const Geoposition& position) OVERRIDE;
 
   // Callback from the LocationArbitrator. Public for testing.
   void OnLocationUpdate(const Geoposition& 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 GeolocationProviderImpl is always
   // instantiated on the same thread. Ownership is NOT returned.
   static GeolocationProviderImpl* GetInstance();
 
+  bool user_did_opt_into_location_services_for_testing() {
+    return user_did_opt_into_location_services_;
+  }
+
  protected:
   friend struct DefaultSingletonTraits<GeolocationProviderImpl>;
   GeolocationProviderImpl();
   virtual ~GeolocationProviderImpl();
 
   // Useful for injecting mock geolocation arbitrator in tests.
   virtual LocationArbitrator* CreateArbitrator();
 
  private:
-  typedef std::pair<LocationUpdateCallback, bool> LocationUpdateInfo;
-  typedef std::list<LocationUpdateInfo> 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(bool use_high_accuracy);
 
   // 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 Geoposition& position);
 
   // Thread
   virtual void Init() OVERRIDE;
   virtual void CleanUp() OVERRIDE;
 
-  // Only used on the IO thread
-  CallbackList callbacks_;
+  base::CallbackList<void(const Geoposition&)> high_accuracy_callbacks_;
+  base::CallbackList<void(const Geoposition&)> low_accuracy_callbacks_;
+
   bool user_did_opt_into_location_services_;
   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.
   LocationArbitrator* arbitrator_;
 
   DISALLOW_COPY_AND_ASSIGN(GeolocationProviderImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_GEOLOCATION_GEOLOCATION_PROVIDER_IMPL_H_