Adding platform support check for NetworkObserver

Review URL: https://codereview.chromium.org/1454313002

Cr-Commit-Position: refs/heads/master@{#363020}

net/android/network_change_notifier_android.cc

@@ -59,6 +59,7 @@
 
 #include "net/android/network_change_notifier_android.h"
 
+#include "base/android/build_info.h"
 #include "base/threading/thread.h"
 #include "net/base/address_tracker_linux.h"
 #include "net/dns/dns_config_service_posix.h"
@@ -162,6 +163,18 @@ void NetworkChangeNotifierAndroid::GetCurrentMaxBandwidthAndConnectionType(
                                                      connection_type);
 }
 
+void NetworkChangeNotifierAndroid::ForceNetworkHandlesSupportedForTesting() {
+  force_network_handles_supported_for_testing_ = true;
+}
+
+bool NetworkChangeNotifierAndroid::AreNetworkHandlesCurrentlySupported() const {
+  // Notifications for API using NetworkHandles and querying using
+  // NetworkHandles only implemented for Android versions >= L.
+  return force_network_handles_supported_for_testing_ ||
+         (base::android::BuildInfo::GetInstance()->sdk_int() >=
+          base::android::SDK_VERSION_LOLLIPOP);
+}
+
 void NetworkChangeNotifierAndroid::GetCurrentConnectedNetworks(
     NetworkChangeNotifier::NetworkList* networks) const {
   delegate_->GetCurrentlyConnectedNetworks(networks);
@@ -222,7 +235,8 @@ NetworkChangeNotifierAndroid::NetworkChangeNotifierAndroid(
     : NetworkChangeNotifier(NetworkChangeCalculatorParamsAndroid()),
       delegate_(delegate),
       dns_config_service_thread_(
-          new DnsConfigServiceThread(dns_config_for_testing)) {
+          new DnsConfigServiceThread(dns_config_for_testing)),
+      force_network_handles_supported_for_testing_(false) {
   CHECK_EQ(NetId::INVALID, NetworkChangeNotifier::kInvalidNetworkHandle)
       << "kInvalidNetworkHandle doesn't match NetId::INVALID";
   delegate_->AddObserver(this);

net/android/network_change_notifier_android.h

@@ -52,6 +52,7 @@ class NET_EXPORT_PRIVATE NetworkChangeNotifierAndroid
   void GetCurrentMaxBandwidthAndConnectionType(
       double* max_bandwidth_mbps,
       ConnectionType* connection_type) const override;
+  bool AreNetworkHandlesCurrentlySupported() const override;
   void GetCurrentConnectedNetworks(NetworkList* network_list) const override;
   ConnectionType GetCurrentNetworkConnectionType(
       NetworkHandle network) const override;
@@ -78,6 +79,9 @@ class NET_EXPORT_PRIVATE NetworkChangeNotifierAndroid
 
   class DnsConfigServiceThread;
 
+  // Enable NetworkHandles support for tests.
+  void ForceNetworkHandlesSupportedForTesting();
+
   NetworkChangeNotifierAndroid(NetworkChangeNotifierDelegateAndroid* delegate,
                                const DnsConfig* dns_config_for_testing);
 
@@ -85,6 +89,7 @@ class NET_EXPORT_PRIVATE NetworkChangeNotifierAndroid
 
   NetworkChangeNotifierDelegateAndroid* const delegate_;
   scoped_ptr<DnsConfigServiceThread> dns_config_service_thread_;
+  bool force_network_handles_supported_for_testing_;
 
   DISALLOW_COPY_AND_ASSIGN(NetworkChangeNotifierAndroid);
 };

net/android/network_change_notifier_android_unittest.cc

@@ -317,6 +317,10 @@ class NetworkChangeNotifierAndroidTest
         &other_connection_type_observer_);
   }
 
+  void ForceNetworkHandlesSupportedForTesting() {
+    notifier_->ForceNetworkHandlesSupportedForTesting();
+  }
+
   NetworkChangeNotifierObserver connection_type_observer_;
   NetworkChangeNotifierObserver other_connection_type_observer_;
   NetworkChangeNotifier::DisableForTest disable_for_test_;
@@ -387,6 +391,8 @@ TEST_F(NetworkChangeNotifierAndroidTest, InitialSignal) {
 }
 
 TEST_F(NetworkChangeNotifierAndroidTest, NetworkCallbacks) {
+  ForceNetworkHandlesSupportedForTesting();
+
   TestNetworkObserver network_observer;
   NetworkChangeNotifier::AddNetworkObserver(&network_observer);
 

net/base/network_change_notifier.cc

@@ -633,8 +633,17 @@ double NetworkChangeNotifier::GetMaxBandwidthForConnectionSubtype(
   return std::numeric_limits<double>::infinity();
 }
 
+// static
+bool NetworkChangeNotifier::AreNetworkHandlesSupported() {
+  if (g_network_change_notifier) {
+    return g_network_change_notifier->AreNetworkHandlesCurrentlySupported();
+  }
+  return false;
+}
+
 // static
 void NetworkChangeNotifier::GetConnectedNetworks(NetworkList* network_list) {
+  DCHECK(AreNetworkHandlesSupported());
   if (g_network_change_notifier) {
     g_network_change_notifier->GetCurrentConnectedNetworks(network_list);
   } else {
@@ -645,6 +654,7 @@ void NetworkChangeNotifier::GetConnectedNetworks(NetworkList* network_list) {
 // static
 NetworkChangeNotifier::ConnectionType
 NetworkChangeNotifier::GetNetworkConnectionType(NetworkHandle network) {
+  DCHECK(AreNetworkHandlesSupported());
   return g_network_change_notifier
              ? g_network_change_notifier->GetCurrentNetworkConnectionType(
                    network)
@@ -654,6 +664,7 @@ NetworkChangeNotifier::GetNetworkConnectionType(NetworkHandle network) {
 // static
 NetworkChangeNotifier::NetworkHandle
 NetworkChangeNotifier::GetDefaultNetwork() {
+  DCHECK(AreNetworkHandlesSupported());
   return g_network_change_notifier
              ? g_network_change_notifier->GetCurrentDefaultNetwork()
              : kInvalidNetworkHandle;
@@ -838,6 +849,7 @@ void NetworkChangeNotifier::AddMaxBandwidthObserver(
 }
 
 void NetworkChangeNotifier::AddNetworkObserver(NetworkObserver* observer) {
+  DCHECK(AreNetworkHandlesSupported());
   if (g_network_change_notifier) {
     g_network_change_notifier->network_observer_list_->AddObserver(observer);
   }
@@ -883,6 +895,7 @@ void NetworkChangeNotifier::RemoveMaxBandwidthObserver(
 }
 
 void NetworkChangeNotifier::RemoveNetworkObserver(NetworkObserver* observer) {
+  DCHECK(AreNetworkHandlesSupported());
   if (g_network_change_notifier) {
     g_network_change_notifier->network_observer_list_->RemoveObserver(observer);
   }
@@ -978,6 +991,10 @@ void NetworkChangeNotifier::GetCurrentMaxBandwidthAndConnectionType(
           : GetMaxBandwidthForConnectionSubtype(SUBTYPE_UNKNOWN);
 }
 
+bool NetworkChangeNotifier::AreNetworkHandlesCurrentlySupported() const {
+  return false;
+}
+
 void NetworkChangeNotifier::GetCurrentConnectedNetworks(
     NetworkList* network_list) const {
   network_list->clear();

net/base/network_change_notifier.h

@@ -291,16 +291,24 @@ class NET_EXPORT NetworkChangeNotifier {
   // TODO(jkarlin): Rename to GetMaxBandwidthMbpsForConnectionSubtype.
   static double GetMaxBandwidthForConnectionSubtype(ConnectionSubtype subtype);
 
+  // Returns true if the platform supports use of APIs based on NetworkHandles.
+  // Public methods that use NetworkHandles are GetNetworkConnectionType(),
+  // GetNetworkConnectionType(), GetDefaultNetwork(), AddNetworkObserver(),
+  // RemoveNetworkObserver(), and all public NetworkObserver methods.
+  static bool AreNetworkHandlesSupported();
+
   // Sets |network_list| to a list of all networks that are currently connected.
   // Only implemented for Android (Lollipop and newer), leaves |network_list|
-  // empty when unimplemented.
+  // empty when unimplemented. Requires NetworkHandles support, see
+  // AreNetworkHandlesSupported().
   static void GetConnectedNetworks(NetworkList* network_list);
 
   // Returns the type of connection |network| uses. Note that this may vary
   // slightly over time (e.g. CONNECTION_2G to CONNECTION_3G). If |network|
   // is no longer connected, it will return CONNECTION_UNKNOWN.
   // Only implemented for Android (Lollipop and newer), returns
-  // CONNECTION_UNKNOWN when unimplemented.
+  // CONNECTION_UNKNOWN when unimplemented. Requires NetworkHandles support,
+  // see AreNetworkHandlesSupported().
   static ConnectionType GetNetworkConnectionType(NetworkHandle network);
 
   // Returns the device's current default network connection. This is the
@@ -310,6 +318,7 @@ class NET_EXPORT NetworkChangeNotifier {
   // there is no default connected network.
   // Only implemented for Android (Lollipop and newer), returns
   // |kInvalidNetworkHandle| when unimplemented.
+  // Requires NetworkHandles support, see AreNetworkHandlesSupported().
   static NetworkHandle GetDefaultNetwork();
 
   // Retrieve the last read DnsConfig. This could be expensive if the system has
@@ -481,6 +490,7 @@ class NET_EXPORT NetworkChangeNotifier {
   virtual void GetCurrentMaxBandwidthAndConnectionType(
       double* max_bandwidth_mbps,
       ConnectionType* connection_type) const;
+  virtual bool AreNetworkHandlesCurrentlySupported() const;
   virtual void GetCurrentConnectedNetworks(NetworkList* network_list) const;
   virtual ConnectionType GetCurrentNetworkConnectionType(
       NetworkHandle network) const;