Provide NetworkChangeNotifierAndroid with the actual initial connection type.

net/android/network_change_notifier_delegate_android.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 NET_ANDROID_NETWORK_CHANGE_NOTIFIER_DELEGATE_ANDROID_H_
 #define NET_ANDROID_NETWORK_CHANGE_NOTIFIER_DELEGATE_ANDROID_H_
 
 #include "base/android/jni_android.h"
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
 #include "base/observer_list_threadsafe.h"
 #include "base/threading/thread_checker.h"
 #include "net/base/network_change_notifier.h"
 
 namespace net {
 
 // Delegate used to thread-safely notify NetworkChangeNotifierAndroid whenever a
 // network connection change notification is signaled by the Java side (on the
 // JNI thread).
 // All the methods exposed below must be called exclusively on the JNI thread
@@ skipping 22 matching lines @@
 
   // Called from NetworkChangeNotifierAndroid.java on the JNI thread whenever
   // the connection type changes. This updates the current connection type seen
   // by this class and forwards the notification to the observers that
   // subscribed through AddObserver().
   void NotifyConnectionTypeChanged(JNIEnv* env,
                                    jobject obj,
                                    jint new_connection_type);
   jint GetConnectionType(JNIEnv* env, jobject obj) const;
 
-  // These methods can be called on any thread. Note that the provided observer
-  // will be notified on the thread AddObserver() is called on.
+  // These methods can be called on any thread. The provided observer will be
+  // notified on the thread AddObserver() is called on. Note that calling this
+  // method schedules an initial notification that lets the observer initialize
+  // its connection type.
   void AddObserver(Observer* observer);

[Ryan Sleevi, 2012/12/19 17:38:16]

Can you not just have AddObserver return the initial state when adding?

[Philippe, 2012/12/19 17:52:23]

I might be missing something but AddObserver() can be called from the I/O
thread. So if I read |connection_type_| in AddObserver(), ideally this should be
guarded by a lock. We might accept to read a possibly outdated value (without
using a lock) in practice. Is it what you meant?

[Ryan Sleevi, 2012/12/19 18:07:57]

Yeah, you'd still have to have a lock.

   void RemoveObserver(Observer* observer);
 
   // Exposed for testing.
   void ForceConnectivityState(ConnectivityState state);
 
   // Initializes JNI bindings.
   static bool Register(JNIEnv* env);
 
  private:
-  friend class NetworkChangeNotifierDelegateAndroidTest;
+  friend class BaseNetworkChangeNotifierAndroidTest;
 
   typedef NetworkChangeNotifier::ConnectionType ConnectionType;
 
+  // Provides the newly added observer with an initial connection type.
+  void SendInitialNotification();
+
   base::ThreadChecker thread_checker_;
+  scoped_refptr<base::SingleThreadTaskRunner> jni_task_runner_;
+  base::WeakPtrFactory<NetworkChangeNotifierDelegateAndroid> weak_ptr_factory_;
+  base::WeakPtr<NetworkChangeNotifierDelegateAndroid> weak_ptr_;
+
   scoped_refptr<ObserverListThreadSafe<Observer> > observers_;
-  scoped_refptr<base::SingleThreadTaskRunner> jni_task_runner_;
   base::android::ScopedJavaGlobalRef<jobject> java_network_change_notifier_;
   ConnectionType connection_type_;
 
   DISALLOW_COPY_AND_ASSIGN(NetworkChangeNotifierDelegateAndroid);
 };
 
 }  // namespace net
 
 #endif  // NET_ANDROID_NETWORK_CHANGE_NOTIFIER_DELEGATE_H_