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+// Copyright 2013 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.
+
+// A wifi data provider provides wifi data from the device that is used by a
+// NetworkLocationProvider to obtain a position fix. We use a singleton
+// instance of the wifi data provider, which is used by multiple
+// NetworkLocationProvider objects.
+//
+// This file provides WifiDataProvider, which provides static methods to
+// access the singleton instance. The singleton instance uses a private
+// implementation to abstract across platforms and also to allow mock providers
+// to be used for testing.
+//
+// This file also provides WifiDataProviderImplBase, a base class which
+// provides common functionality for the private implementations.
+
+#ifndef CONTENT_BROWSER_GEOLOCATION_WIFI_DATA_PROVIDER_H_
+#define CONTENT_BROWSER_GEOLOCATION_WIFI_DATA_PROVIDER_H_
+
+#include <set>
+
+#include "base/basictypes.h"
+#include "base/bind.h"
+#include "base/callback.h"
+#include "base/memory/ref_counted.h"
+#include "base/message_loop/message_loop.h"
+#include "base/strings/string16.h"
+#include "base/strings/string_util.h"
+#include "content/browser/geolocation/wifi_data.h"
+#include "content/common/content_export.h"
+
+namespace content {
+
+class WifiDataProvider;
+
+// See class WifiDataProvider for the public client API.
+// WifiDataProvider uses containment to hide platform-specific implementation
+// details from common code. This class provides common functionality for these
+// contained implementation classes. This is a modified pimpl pattern.
+class CONTENT_EXPORT WifiDataProviderImplBase
+ : public base::RefCountedThreadSafe<WifiDataProviderImplBase> {
+ public:
+ WifiDataProviderImplBase();
+
+ // Tells the provider to start looking for data. Callbacks will start
+ // receiving notifications after this call.
+ virtual void StartDataProvider() = 0;
+
+ // Tells the provider to stop looking for data. Callbacks will stop
+ // receiving notifications after this call.
+ virtual void StopDataProvider() = 0;
+
+ // Provides whatever data the provider has, which may be nothing. Return
+ // value indicates whether this is all the data the provider could ever
+ // obtain.
+ virtual bool GetData(WifiData* data) = 0;
+
+ // Sets the container of this class, which is of type WifiDataProvider.
+ // This is required to pass as a parameter when calling a callback.
+ void SetContainer(WifiDataProvider* container);
+
+ typedef base::Callback<void(WifiDataProvider*)> WifiDataUpdateCallback;
+
+ void AddCallback(WifiDataUpdateCallback* callback);
+
+ bool RemoveCallback(WifiDataUpdateCallback* callback);
+
+ bool has_callbacks() const;
+
+ protected:
+ friend class base::RefCountedThreadSafe<WifiDataProviderImplBase>;
+ virtual ~WifiDataProviderImplBase();
+
+ typedef std::set<WifiDataUpdateCallback*> CallbackSet;
+
+ // Runs all callbacks via a posted task, so we can unwind callstack here and
+ // avoid client reentrancy.
+ void RunCallbacks();
+
+ bool CalledOnClientThread() const;
+
+ base::MessageLoop* client_loop() const;
+
+ private:
+ void DoRunCallbacks();
+
+ WifiDataProvider* container_;
+
+ // Reference to the client's message loop. All callbacks should happen in this
+ // context.
+ base::MessageLoop* client_loop_;
+
+ CallbackSet callbacks_;
+
+ DISALLOW_COPY_AND_ASSIGN(WifiDataProviderImplBase);
+};
+
+// A wifi data provider
+//
+// We use a singleton instance of this class which is shared by multiple network
+// location providers. These location providers access the instance through the
+// Register and Unregister methods.
+class CONTENT_EXPORT WifiDataProvider {
+ public:
+ // Sets the factory function which will be used by Register to create the
+ // implementation used by the singleton instance. This factory approach is
+ // used both to abstract accross platform-specific implementations and to
+ // inject mock implementations for testing.
+ typedef WifiDataProviderImplBase* (*ImplFactoryFunction)(void);
+ static void SetFactory(ImplFactoryFunction factory_function_in);
+
+ // Resets the factory function to the default.
+ static void ResetFactory();
+
+ typedef base::Callback<void(WifiDataProvider*)> WifiDataUpdateCallback;
+
+ // Registers a callback, which will be run whenever new data is available.
+ // Instantiates the singleton if necessary, and always returns it.
+ static WifiDataProvider* Register(WifiDataUpdateCallback* callback);
+
+ // Removes a callback. If this is the last callback, deletes the singleton
+ // instance. Return value indicates success.
+ static bool Unregister(WifiDataUpdateCallback* callback);
+
+ // Provides whatever data the provider has, which may be nothing. Return
+ // value indicates whether this is all the data the provider could ever
+ // obtain.
+ bool GetData(WifiData* data);
+
+ private:
+ // Private constructor and destructor, callers access singleton through
+ // Register and Unregister.
+ WifiDataProvider();
+ virtual ~WifiDataProvider();
+
+ void AddCallback(WifiDataUpdateCallback* callback);
+ bool RemoveCallback(WifiDataUpdateCallback* callback);
+ bool has_callbacks() const;
+
+ void StartDataProvider();
+ void StopDataProvider();
+
+ static WifiDataProviderImplBase* DefaultFactoryFunction();
+
+ // The singleton-like instance of this class. (Not 'true' singleton, as it
+ // may go through multiple create/destroy/create cycles per process instance,
+ // e.g. when under test).
+ static WifiDataProvider* instance_;
+
+ // The factory function used to create the singleton instance.
+ static ImplFactoryFunction factory_function_;
+
+ // The internal implementation.
+ scoped_refptr<WifiDataProviderImplBase> impl_;
+
+ DISALLOW_COPY_AND_ASSIGN(WifiDataProvider);
+};
+
+} // namespace content
+
+#endif // CONTENT_BROWSER_GEOLOCATION_WIFI_DATA_PROVIDER_H_