[CrOS Cellular] Fix notification of active network technology change

This is a followup to https://crrev.com/c/1977309 to fix cellular
network technology icon inconsistency. The previous CL adds checks for
network technology changes when checking for active network changes.
This CL makes changes to NetworkStateHandler that ensures that these
checks are run for network technology property changes in the first
place. Unit tests were also added.

Fixed: 994445
Change-Id: I7790c3794f27c26e099eaab9e7db718b00aff73e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1982238Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Commit-Queue: Azeem Arshad <azeemarshad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#728054}

chromeos/network/network_state_handler.cc

@@ -1413,6 +1413,7 @@ void NetworkStateHandler::UpdateNetworkServiceProperty(
   if (key == shill::kSignalStrengthProperty || key == shill::kWifiBSsid ||
       key == shill::kWifiFrequency ||
       key == shill::kWifiFrequencyListProperty ||
+      key == shill::kNetworkTechnologyProperty ||
       (key == shill::kDeviceProperty && value_str == "/")) {
     // Uninteresting update. This includes 'Device' property changes to "/"
     // (occurs before just a service is removed).
@@ -1421,9 +1422,12 @@ void NetworkStateHandler::UpdateNetworkServiceProperty(
       return;
     // Otherwise do not trigger 'default network changed'.
     notify_default = false;
-    // Notify signal strength changes for active networks.
-    if (key == shill::kSignalStrengthProperty)
+    // Notify signal strength and network technology changes for active
+    // networks.
+    if (key == shill::kSignalStrengthProperty ||
+        key == shill::kNetworkTechnologyProperty) {
       notify_active = true;
+    }
   }
 
   LogPropertyUpdated(network, key, value);

chromeos/network/network_state_handler_unittest.cc

@@ -1636,6 +1636,25 @@ TEST_F(NetworkStateHandlerTest, NetworkActiveNetworksStateChanged) {
   base::RunLoop().RunUntilIdle();
   EXPECT_EQ(1u, test_observer_->active_network_change_count());
 
+  // Activate cellular network so that it's part of active network list.
+  service_test_->SetServiceProperty(
+      kShillManagerClientStubCellular, shill::kActivationStateProperty,
+      base::Value(shill::kActivationStateActivating));
+  base::RunLoop().RunUntilIdle();
+  expected_active_network_paths = {kShillManagerClientStubCellular};
+  EXPECT_EQ(expected_active_network_paths,
+            test_observer_->active_network_paths());
+  // Test that network technology change signals the observer.
+  test_observer_->reset_change_counts();
+  service_test_->SetServiceProperty(kShillManagerClientStubCellular,
+                                    shill::kNetworkTechnologyProperty,
+                                    base::Value(shill::kNetworkTechnologyUmts));
+  base::RunLoop().RunUntilIdle();
+  EXPECT_EQ(1u, test_observer_->active_network_change_count());
+  // Remove cellular service.
+  service_test_->RemoveService(kShillManagerClientStubCellular);
+  base::RunLoop().RunUntilIdle();
+
   // Add two Tether networks.
   test_observer_->reset_change_counts();
   network_state_handler_->SetTetherTechnologyState(