[ios] Disable preload when offline.

Bug: 1011944
Change-Id: Ie05f722e6fd79571d062d0250986002867b503f7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1849137
Commit-Queue: Justin Cohen <justincohen@chromium.org>
Auto-Submit: Justin Cohen <justincohen@chromium.org>
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#704208}

ios/chrome/browser/prerender/preload_controller.mm

@@ -272,6 +272,7 @@ class PreloadJavaScriptDialogPresenter : public web::JavaScriptDialogPresenter {
   return !IsPrerenderTabEvictionExperimentalGroup() && self.preferenceEnabled &&
          !ios::device_util::IsSingleCoreDevice() &&
          ios::device_util::RamIsAtLeast512Mb() &&
+         !net::NetworkChangeNotifier::IsOffline() &&
          (!self.wifiOnly || !self.usingWWAN);
 }
 

ios/chrome/browser/prerender/preload_controller_unittest.mm

@@ -90,6 +90,11 @@ class PreloadControllerTest : public PlatformTest {
         net::NetworkChangeNotifier::CONNECTION_WIFI);
   }
 
+  void SimulateOffline() {
+    network_change_notifier_->SimulateNetworkConnectionChange(
+        net::NetworkChangeNotifier::CONNECTION_NONE);
+  }
+
   void SimulateCellularConnection() {
     network_change_notifier_->SimulateNetworkConnectionChange(
         net::NetworkChangeNotifier::CONNECTION_3G);
@@ -133,13 +138,16 @@ TEST_F(PreloadControllerTest, DontPreloadNonWebURLs) {
 
 TEST_F(PreloadControllerTest, TestIsPrerenderingEnabled_preloadAlways) {
   // With the "Preload Webpages" setting set to "Always", prerendering is
-  // enabled regardless of network type.
+  // enabled regardless of network type, unless offline.
   PreloadWebpagesAlways();
 
   SimulateWiFiConnection();
   EXPECT_TRUE(controller_.enabled || ios::device_util::IsSingleCoreDevice() ||
               !ios::device_util::RamIsAtLeast512Mb());
 
+  SimulateOffline();
+  EXPECT_FALSE(controller_.enabled);
+
   SimulateCellularConnection();
   EXPECT_TRUE(controller_.enabled || ios::device_util::IsSingleCoreDevice() ||
               !ios::device_util::RamIsAtLeast512Mb());
@@ -154,6 +162,9 @@ TEST_F(PreloadControllerTest, TestIsPrerenderingEnabled_preloadWiFiOnly) {
   EXPECT_TRUE(controller_.enabled || ios::device_util::IsSingleCoreDevice() ||
               !ios::device_util::RamIsAtLeast512Mb());
 
+  SimulateOffline();
+  EXPECT_FALSE(controller_.enabled);
+
   SimulateCellularConnection();
   EXPECT_FALSE(controller_.enabled);
 }
@@ -166,6 +177,9 @@ TEST_F(PreloadControllerTest, TestIsPrerenderingEnabled_preloadNever) {
   SimulateWiFiConnection();
   EXPECT_FALSE(controller_.enabled);
 
+  SimulateOffline();
+  EXPECT_FALSE(controller_.enabled);
+
   SimulateCellularConnection();
   EXPECT_FALSE(controller_.enabled);
 }