Observe IP address change in connectivity_checker.

Observing ConnectionType alone doesn't detect network
changes on some OEM platforms. Observe IP address
to address this.

BUG=

Review URL: https://codereview.chromium.org/995933002

Cr-Commit-Position: refs/heads/master@{#320148}

chromecast/net/connectivity_checker.cc

@@ -60,12 +60,15 @@ void ConnectivityChecker::Initialize() {
   url_request_context_.reset(builder.Build());
 
   net::NetworkChangeNotifier::AddConnectionTypeObserver(this);
+  net::NetworkChangeNotifier::AddIPAddressObserver(this);
   loop_proxy_->PostTask(FROM_HERE,
                         base::Bind(&ConnectivityChecker::Check, this));
 }
 
 ConnectivityChecker::~ConnectivityChecker() {
   DCHECK(loop_proxy_.get());
+  net::NetworkChangeNotifier::RemoveIPAddressObserver(this);
+  net::NetworkChangeNotifier::RemoveConnectionTypeObserver(this);
   loop_proxy_->DeleteSoon(FROM_HERE, url_request_context_.release());
   loop_proxy_->DeleteSoon(FROM_HERE, url_request_.release());
 }
@@ -116,13 +119,21 @@ void ConnectivityChecker::Check() {
 
 void ConnectivityChecker::OnConnectionTypeChanged(
     net::NetworkChangeNotifier::ConnectionType type) {
+  VLOG(2) << "OnConnectionTypeChanged " << type;
   if (type == net::NetworkChangeNotifier::CONNECTION_NONE)
     SetConnectivity(false);
 
   Cancel();
   Check();
 }
 
+void ConnectivityChecker::OnIPAddressChanged() {
+  VLOG(2) << "OnIPAddressChanged";
+
+  Cancel();
+  Check();
+}
+
 void ConnectivityChecker::OnResponseStarted(net::URLRequest* request) {
   int http_response_code =
       (request->status().is_success() &&

chromecast/net/connectivity_checker.h

@@ -28,7 +28,8 @@ namespace chromecast {
 class ConnectivityChecker
     : public base::RefCountedThreadSafe<ConnectivityChecker>,
       public net::URLRequest::Delegate,
-      public net::NetworkChangeNotifier::ConnectionTypeObserver {
+      public net::NetworkChangeNotifier::ConnectionTypeObserver,
+      public net::NetworkChangeNotifier::IPAddressObserver {
  public:
   class ConnectivityObserver {
    public:
@@ -72,6 +73,9 @@ class ConnectivityChecker
   void OnConnectionTypeChanged(
       net::NetworkChangeNotifier::ConnectionType type) override;
 
+  // net::NetworkChangeNotifier::IPAddressObserver implementation:
+  void OnIPAddressChanged() override;
+
   // Cancels current connectivity checking in progress.
   void Cancel();