[chromecast] Smooth out OnNetworkChanged event to avoid rapid flipping

between setup state 50 and 60.

BUG=internal b/26017446

Review URL: https://codereview.chromium.org/1496323003

Cr-Commit-Position: refs/heads/master@{#368482}

2 files changed, 26 insertions, 2 deletions

diff --git a/chromecast/net/connectivity_checker_impl.cc b/chromecast/net/connectivity_checker_impl.cc
index 4bfc52f..a79571c 100644
--- a/chromecast/net/connectivity_checker_impl.cc
+++ b/chromecast/net/connectivity_checker_impl.cc
@@ -36,6 +36,11 @@ const unsigned int kRequestTimeoutInSeconds = 3;
 const char kDefaultConnectivityCheckUrl[] =
     "https://clients3.google.com/generate_204";
 
+// Delay notification of network change events to smooth out rapid flipping.
+// Histogram "Cast.Network.Down.Duration.In.Seconds" shows 40% of network
+// downtime is less than 3 seconds.
+const char kNetworkChangedDelayInSeconds = 3;
+
 }  // namespace
 
 ConnectivityCheckerImpl::ConnectivityCheckerImpl(
@@ -43,7 +48,9 @@ ConnectivityCheckerImpl::ConnectivityCheckerImpl(
     : ConnectivityChecker(),
       task_runner_(task_runner),
       connected_(false),
-      check_errors_(0) {
+      connection_type_(net::NetworkChangeNotifier::CONNECTION_NONE),
+      check_errors_(0),
+      network_changed_pending_(false) {
   DCHECK(task_runner_.get());
   task_runner->PostTask(FROM_HERE,
                         base::Bind(&ConnectivityCheckerImpl::Initialize, this));
@@ -125,9 +132,22 @@ void ConnectivityCheckerImpl::Check() {
 void ConnectivityCheckerImpl::OnNetworkChanged(
     net::NetworkChangeNotifier::ConnectionType type) {
   VLOG(2) << "OnNetworkChanged " << type;
+  connection_type_ = type;
+
+  if (network_changed_pending_)
+    return;
+  network_changed_pending_ = true;
+  base::MessageLoop::current()->PostDelayedTask(
+      FROM_HERE,
+      base::Bind(&ConnectivityCheckerImpl::OnNetworkChangedInternal, this),
+      base::TimeDelta::FromSeconds(kNetworkChangedDelayInSeconds));
+}
+
+void ConnectivityCheckerImpl::OnNetworkChangedInternal() {
+  network_changed_pending_ = false;
   Cancel();
 
-  if (type == net::NetworkChangeNotifier::CONNECTION_NONE) {
+  if (connection_type_ == net::NetworkChangeNotifier::CONNECTION_NONE) {
     SetConnected(false);
     return;
   }
diff --git a/chromecast/net/connectivity_checker_impl.h b/chromecast/net/connectivity_checker_impl.h
index 1db5dfb..0b40b51 100644
--- a/chromecast/net/connectivity_checker_impl.h
+++ b/chromecast/net/connectivity_checker_impl.h
@@ -57,6 +57,8 @@ class ConnectivityCheckerImpl
   void OnNetworkChanged(
       net::NetworkChangeNotifier::ConnectionType type) override;
 
+  void OnNetworkChangedInternal();
+
   // Cancels current connectivity checking in progress.
   void Cancel();
 
@@ -74,8 +76,10 @@ class ConnectivityCheckerImpl
   scoped_ptr<net::URLRequest> url_request_;
   const scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
   bool connected_;
+  net::NetworkChangeNotifier::ConnectionType connection_type_;
   // Number of connectivity check errors.
   unsigned int check_errors_;
+  bool network_changed_pending_;
   // Timeout handler for connectivity checks.
   // Note: Cancelling this timeout can cause the destructor for this class to be
   //       to be called.