Add device location reporting

content/browser/geolocation/geolocation_provider.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_H_
 #define CONTENT_BROWSER_GEOLOCATION_GEOLOCATION_PROVIDER_H_
 #pragma once
 
 #include <map>
 
 #include "base/threading/thread.h"
 #include "content/browser/geolocation/geolocation_observer.h"
 #include "content/common/content_export.h"
 #include "content/common/geoposition.h"
 
 class GeolocationArbitrator;
 
 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
-// observers which will be notified of location updates. Underlying location
-// arbitrator will only be enabled whilst there is at least one observer
-// registered.
+// This is the main API to the geolocation subsystem. The application will hold
+// a single instance of this class and can register multiple observers which
+// will be notified of location updates. 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 observer registered. The arbitrator and the location providers it
+// uses run on a separate Geolocation thread.
 class CONTENT_EXPORT GeolocationProvider
     : public base::Thread, public GeolocationObserver {
  public:
-  GeolocationProvider();
-
-  // Must be called from the same thread as the GeolocationProvider was created
-  // on. The GeolocationObserverOptions passed are used as a 'hint' for the
-  // provider preferences for this particular observer, however the observer
-  // could receive callbacks for best available locations from any active
-  // provider whilst it is registered.
-  // If an existing observer is added a second time it's options are updated
+  // The GeolocationObserverOptions passed are used as a 'hint' for the provider
+  // preferences for this particular observer, however the observer could
+  // receive callbacks 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);
 
   void OnPermissionGranted();
   bool HasPermissionBeenGranted() const;
 
   // GeolocationObserver
   virtual void OnLocationUpdate(const Geoposition& position) OVERRIDE;
 
   // Gets a pointer to the singleton instance of the location relayer, which
-  // is in turn bound to the browser's global context objects. Ownership is NOT
-  // returned.
+  // 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();
 
   typedef std::map<GeolocationObserver*, GeolocationObserverOptions>
       ObserverMap;
 
- private:
+ protected:

[joth, 2012/04/23 10:05:14]

comment why protected. (derivation required for test code only)

[bartfab (slow), 2012/04/23 12:21:28]

Done.

   friend struct DefaultSingletonTraits<GeolocationProvider>;
+  GeolocationProvider();
   virtual ~GeolocationProvider();
 
-  bool OnClientThread() const;
+ private:
+  static bool OnIOThread();
   bool OnGeolocationThread() const;
 
   // When the observer list changes, we may start the thread and the required
   // providers, or stop them.
   void OnObserversChanged();
 
   // Stop the providers when there are no more observers. Note that once our
   // thread is started, we'll keep it alive (but with no pending messages).
   void StopProviders();
 
   // Starts or updates the observers' geolocation options
   // (delegates to arbitrator).
   void StartProviders(const GeolocationObserverOptions& options);
 
   // Update the providers on the geolocation thread, which must be running.
   void InformProvidersPermissionGranted();
 
   // Notifies observers when a new position fix is available.
   void NotifyObservers(const Geoposition& position);
 
   // Thread
   virtual void Init() OVERRIDE;
   virtual void CleanUp() OVERRIDE;
 
-  scoped_refptr<base::MessageLoopProxy> client_loop_;
-
-  // Only used on client thread
+  // Only used on the IO thread
   ObserverMap observers_;
   bool is_permission_granted_;
   Geoposition position_;
 
   // Only to be used on the geolocation thread.
   GeolocationArbitrator* arbitrator_;
 
   DISALLOW_COPY_AND_ASSIGN(GeolocationProvider);
 };
 
 #endif  // CONTENT_BROWSER_GEOLOCATION_GEOLOCATION_PROVIDER_H_