Implemented lazy portal detection.

chrome/browser/chromeos/net/network_portal_detector.cc

Index: chrome/browser/chromeos/net/network_portal_detector.cc
diff --git a/chrome/browser/chromeos/net/network_portal_detector.cc b/chrome/browser/chromeos/net/network_portal_detector.cc
index 4a2b6a51587106017b0ab5717962df32a21d13c4..372696b5d8b3541ecfb8a29a7d4a5fffc05454c8 100644
--- a/chrome/browser/chromeos/net/network_portal_detector.cc
+++ b/chrome/browser/chromeos/net/network_portal_detector.cc
@@ -38,6 +38,11 @@ const int kRequestTimeoutSec = 10;
 // Delay before portal detection caused by changes in proxy settings.
 const int kProxyChangeDelayMs = 500;
 
+// Delay between consecutive portal checks for a network in lazy mode.
+// TODO (ygorshenin@): use exponential backoff or normally distributed
+// random variable instead of this.
+const int kLazyCheckIntervalSec = 30;
+
 std::string CaptivePortalStatusString(
     NetworkPortalDetector::CaptivePortalStatus status) {
   switch (status) {
@@ -73,6 +78,8 @@ NetworkPortalDetector::NetworkPortalDetector(
       test_url_(CaptivePortalDetector::kDefaultURL),
       weak_ptr_factory_(this),
       attempt_count_(0),
+      lazy_detection_enabled_(false),
+      lazy_check_interval_(base::TimeDelta::FromSeconds(kLazyCheckIntervalSec)),
       min_time_between_attempts_(
           base::TimeDelta::FromSeconds(kMinTimeBetweenAttemptsSec)),
       request_timeout_(base::TimeDelta::FromSeconds(kRequestTimeoutSec)) {
@@ -170,18 +177,12 @@ void NetworkPortalDetector::OnNetworkManagerChanged(NetworkLibrary* cros) {
 
   if (network_changed || connection_state_changed) {
     attempt_count_ = 0;
-    if (IsPortalCheckPending()) {
-      detection_task_.Cancel();
-      detection_timeout_.Cancel();
-    } else if (IsCheckingForPortal()) {
-      captive_portal_detector_->Cancel();
-    }
-    state_ = STATE_IDLE;
+    CancelPortalDetection();
   }
 
   if (!IsCheckingForPortal() && !IsPortalCheckPending() &&
       Network::IsConnectedState(active_connection_state_) &&
-      attempt_count_ < kMaxRequestAttempts) {
+      (attempt_count_ < kMaxRequestAttempts || lazy_detection_enabled_)) {
     DCHECK(active_network);
 
     // Initiate Captive Portal detection if network's captive
@@ -202,6 +203,24 @@ void NetworkPortalDetector::OnNetworkChanged(chromeos::NetworkLibrary* cros,
   OnNetworkManagerChanged(cros);
 }
 
+void NetworkPortalDetector::EnableLazyDetection() {
+  if (lazy_detection_enabled_)
+    return;
+  VLOG(1) << "Lazy detection mode enabled";
+  lazy_detection_enabled_ = true;
+  if (!IsPortalCheckPending() && !IsCheckingForPortal())
+    DetectCaptivePortal(base::TimeDelta());
+}
+
+void NetworkPortalDetector::DisableLazyDetection() {
+  if (!lazy_detection_enabled_)
+    return;
+  VLOG(1) << "Lazy detection mode disabled";
+  if (attempt_count_ == kMaxRequestAttempts)
+    CancelPortalDetection();
+  lazy_detection_enabled_ = false;
+}
+
 // static
 NetworkPortalDetector* NetworkPortalDetector::CreateInstance() {
   DCHECK(!g_network_portal_detector);
@@ -226,7 +245,7 @@ bool NetworkPortalDetector::IsEnabled() {
 void NetworkPortalDetector::DetectCaptivePortal(const base::TimeDelta& delay) {
   DCHECK(!IsPortalCheckPending());
   DCHECK(!IsCheckingForPortal());
-  DCHECK(attempt_count_ < kMaxRequestAttempts);
+  DCHECK(attempt_count_ < kMaxRequestAttempts || lazy_detection_enabled_);
 
   detection_task_.Cancel();
   detection_timeout_.Cancel();
@@ -236,11 +255,17 @@ void NetworkPortalDetector::DetectCaptivePortal(const base::TimeDelta& delay) {
   if (attempt_count_ > 0) {
     base::TimeTicks now = GetCurrentTimeTicks();
     base::TimeDelta elapsed_time;
+
+    base::TimeDelta delay_between_attempts = min_time_between_attempts_;
+    if (attempt_count_ == kMaxRequestAttempts) {
+      DCHECK(lazy_detection_enabled_);
+      delay_between_attempts = lazy_check_interval_;
+    }
     if (now > attempt_start_time_)
       elapsed_time = now - attempt_start_time_;
-    if (elapsed_time < min_time_between_attempts_ &&
-        min_time_between_attempts_ - elapsed_time > next_attempt_delay_) {
-      next_attempt_delay_ = min_time_between_attempts_ - elapsed_time;
+    if (elapsed_time < delay_between_attempts &&
+        delay_between_attempts - elapsed_time > next_attempt_delay_) {
+      next_attempt_delay_ = delay_between_attempts - elapsed_time;
     }
   } else {
     detection_start_time_ = GetCurrentTimeTicks();
@@ -258,11 +283,17 @@ void NetworkPortalDetector::DetectCaptivePortalTask() {
 
   state_ = STATE_CHECKING_FOR_PORTAL;
 
-  ++attempt_count_;
   attempt_start_time_ = GetCurrentTimeTicks();
 
-  VLOG(1) << "Portal detection started: network=" << active_network_id_ << ", "
-          << "attempt=" << attempt_count_ << " of " << kMaxRequestAttempts;
+  if (attempt_count_ < kMaxRequestAttempts) {
+    ++attempt_count_;
+    VLOG(1) << "Portal detection started: "
+            << "network=" << active_network_id_ << ", "
+            << "attempt=" << attempt_count_ << " of " << kMaxRequestAttempts;
+  } else {
+    DCHECK(lazy_detection_enabled_);
+    VLOG(1) << "Lazy portal detection attempt started";
+  }
 
   captive_portal_detector_->DetectCaptivePortal(
       test_url_,
@@ -288,6 +319,16 @@ void NetworkPortalDetector::PortalDetectionTimeout() {
   OnPortalDetectionCompleted(results);
 }
 
+void NetworkPortalDetector::CancelPortalDetection() {
+  if (IsPortalCheckPending()) {
+    detection_task_.Cancel();
+    detection_timeout_.Cancel();
+  } else if (IsCheckingForPortal()) {
+    captive_portal_detector_->Cancel();
+  }
+  state_ = STATE_IDLE;
+}
+
 void NetworkPortalDetector::OnPortalDetectionCompleted(
     const CaptivePortalDetector::Results& results) {
   DCHECK(CalledOnValidThread());
@@ -304,8 +345,10 @@ void NetworkPortalDetector::OnPortalDetectionCompleted(
 
   NetworkLibrary* cros = CrosLibrary::Get()->GetNetworkLibrary();
   const Network* active_network = cros->active_network();
-  if (!active_network)
+  if (!active_network) {
+    TryLazyDetection();
     return;
+  }
 
   CaptivePortalState state;
   state.response_code = results.response_code;
@@ -342,7 +385,18 @@ void NetworkPortalDetector::OnPortalDetectionCompleted(
     default:
       break;
   }
+
+  TryLazyDetection();
 }
+
+void NetworkPortalDetector::TryLazyDetection() {
+  if (!IsPortalCheckPending() && !IsCheckingForPortal() &&
+      lazy_detection_enabled_) {
+    attempt_count_ = kMaxRequestAttempts;
+    DetectCaptivePortal(base::TimeDelta());
+  }
+}
+
 void NetworkPortalDetector::Observe(
     int type,
     const content::NotificationSource& source,