Fix race condition in NetworkChangeNotifier on Android.

net/android/network_change_notifier_android.h

Index: net/android/network_change_notifier_android.h
diff --git a/net/android/network_change_notifier_android.h b/net/android/network_change_notifier_android.h
index 3c71dc5995bb31fdfacf88b46fc8e37ce2cb8106..ee829b3eb908498ec60155c098597a7a342a9a1c 100644
--- a/net/android/network_change_notifier_android.h
+++ b/net/android/network_change_notifier_android.h
@@ -8,6 +8,7 @@
 #include "base/android/scoped_java_ref.h"
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
+#include "base/synchronization/lock.h"
 #include "net/base/network_change_notifier.h"
 
 namespace net {
@@ -15,21 +16,34 @@ namespace android {
 
 class NetworkChangeNotifier : public net::NetworkChangeNotifier {
  public:
-  NetworkChangeNotifier();
   virtual ~NetworkChangeNotifier();
 
-  void NotifyObservers(JNIEnv* env, jobject obj);
+  // Called from Java on the UI thread.
+  void NotifyObservers(JNIEnv* env, jobject obj, int new_connection_type);
+  jint GetConnectionType(JNIEnv* env, jobject obj);
 
   static bool Register(JNIEnv* env);
 
  private:
+  friend class NetworkChangeNotifierFactory;
+
+  NetworkChangeNotifier();
+
   void CreateJavaObject(JNIEnv* env);
 
+  void SetConnectionType(int connection_type);
+
   // NetworkChangeNotifier:
   virtual net::NetworkChangeNotifier::ConnectionType
       GetCurrentConnectionType() const OVERRIDE;
 
   base::android::ScopedJavaGlobalRef<jobject> java_network_change_notifier_;
+  // TODO(pliard): Use an atomic integer for the connection type without the
+  // lock once a non-subtle atomic integer is available under base/. That might
+  // never happen though.
+  mutable base::Lock lock_;  // Protects the state below.
+  // Wrote from the UI thread, read from any thread.
+  int connection_type_;
 
   DISALLOW_COPY_AND_ASSIGN(NetworkChangeNotifier);
 };