Add NetworkListObserver utility class.

ppapi/tests/test_network_monitor_private.h

Index: ppapi/tests/test_network_monitor_private.h
diff --git a/ppapi/tests/test_network_monitor_private.h b/ppapi/tests/test_network_monitor_private.h
index 00a856a9321bc4e67adcf7e2268a1af378440845..38016d2de93cda0758da11b5e7a96159d61cf4d2 100644
--- a/ppapi/tests/test_network_monitor_private.h
+++ b/ppapi/tests/test_network_monitor_private.h
@@ -10,6 +10,10 @@
 #include "ppapi/c/pp_stdint.h"
 #include "ppapi/tests/test_case.h"
 
+namespace pp {
+class NetworkListPrivate;
+}  // namespace pp
+
 class TestNetworkMonitorPrivate : public TestCase {
  public:
   explicit TestNetworkMonitorPrivate(TestingInstance* instance);
@@ -22,8 +26,10 @@ class TestNetworkMonitorPrivate : public TestCase {
   std::string TestBasic();
   std::string Test2Monitors();
   std::string TestDeleteInCallback();
+  std::string TestListObserver();
 
-  std::string VerifyNetworkList(PP_Resource network_resource);
+  std::string VerifyNetworkListResource(PP_Resource network_resource);
+  std::string VerifyNetworkList(const pp::NetworkListPrivate& network_list);
 };
 
 #endif  // PAPPI_TESTS_TEST_NETWORK_MONITOR_PRIVATE_H_