Make CupsPrintersManager a CrosNetworkConfigObserver

- CupsPrinterManager will now detect for network changes.
- Previously, when the network changes CupsPrintersManager would
  wait until ZeroConfDetector updates with new printers.
- This resulted in a small time frame in which CupsPrintersManager
  would still retain stale printers from the previous network.
- This fixes that bug by clearing the all printers upon a network
  change, ensuring only new printers are populated.

Bug: 779602
Test: unittests, end to end manual
Change-Id: I0efe9e0a2252378bca178dc4b6dcea4da6baa978
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1764677
Commit-Queue: jimmy gong <jimmyxgong@chromium.org>
Reviewed-by: Zentaro Kavanagh <zentaro@chromium.org>
Reviewed-by: Bailey Berro <baileyberro@chromium.org>
Cr-Commit-Position: refs/heads/master@{#693364}

chrome/browser/chromeos/printing/cups_printers_manager.cc

@@ -7,6 +7,7 @@
 #include <map>
 #include <utility>
 
+#include "ash/public/cpp/network_config_service.h"
 #include "base/bind.h"
 #include "base/observer_list.h"
 #include "base/optional.h"
@@ -27,16 +28,20 @@
 #include "chrome/browser/chromeos/printing/zeroconf_printer_detector.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/pref_names.h"
+#include "chromeos/services/network_config/public/mojom/cros_network_config.mojom.h"
 #include "components/policy/policy_constants.h"
 #include "components/pref_registry/pref_registry_syncable.h"
 #include "components/prefs/pref_member.h"
 #include "components/prefs/pref_service.h"
+#include "mojo/public/cpp/bindings/remote.h"
 
 namespace chromeos {
 namespace {
 
-class CupsPrintersManagerImpl : public CupsPrintersManager,
-                                public SyncedPrintersManager::Observer {
+class CupsPrintersManagerImpl
+    : public CupsPrintersManager,
+      public SyncedPrintersManager::Observer,
+      public chromeos::network_config::mojom::CrosNetworkConfigObserver {
  public:
   // Identifiers for each of the underlying PrinterDetectors this
   // class observes.
@@ -67,6 +72,14 @@ class CupsPrintersManagerImpl : public CupsPrintersManager,
     // Add the |auto_usb_printer_configurer_| as an observer.
     AddObserver(&auto_usb_printer_configurer_);
 
+    ash::GetNetworkConfigService(
+        remote_cros_network_config_.BindNewPipeAndPassReceiver());
+
+    chromeos::network_config::mojom::CrosNetworkConfigObserverPtr observer_ptr;
+    cros_network_config_observer_receiver_.Bind(
+        mojo::MakeRequest(&observer_ptr));
+    remote_cros_network_config_->AddObserver(std::move(observer_ptr));
+
     // Prime the printer cache with the saved and enterprise printers.
     printers_.ReplacePrintersInClass(
         PrinterClass::kSaved, synced_printers_manager_->GetSavedPrinters());
@@ -226,6 +239,27 @@ class CupsPrintersManagerImpl : public CupsPrintersManager,
     NotifyObservers({PrinterClass::kEnterprise});
   }
 
+  // mojom::CrosNetworkConfigObserver implementation.
+  void OnActiveNetworksChanged(
+      std::vector<chromeos::network_config::mojom::NetworkStatePropertiesPtr>
+          networks) override {
+    // Clear the network detected printers when the active network changes.
+    // This ensures that connecting to a new network will give us only newly
+    // detected printers.
+    ClearNetworkDetectedPrinters();
+  }
+
+  // mojom::CrosNetworkConfigObserver implementation.
+  void OnNetworkStateChanged(
+      chromeos::network_config::mojom::NetworkStatePropertiesPtr /* network */)
+      override {}
+
+  // mojom::CrosNetworkConfigObserver implementation.
+  void OnNetworkStateListChanged() override {}
+
+  // mojom::CrosNetworkConfigObserver implementation.
+  void OnDeviceStateListChanged() override {}
+
   // Callback for PrinterDetectors.
   void OnPrintersFound(
       int detector_id,
@@ -442,6 +476,13 @@ class CupsPrintersManagerImpl : public CupsPrintersManager,
         PrinterConfigurer::SetupFingerprint(printer);
   }
 
+  // Resets all network detected printer lists.
+  void ClearNetworkDetectedPrinters() {
+    zeroconf_detections_.clear();
+
+    ResetNearbyPrintersLists();
+  }
+
   SEQUENCE_CHECKER(sequence_);
 
   // Source lists for detected printers.
@@ -452,6 +493,10 @@ class CupsPrintersManagerImpl : public CupsPrintersManager,
   SyncedPrintersManager* const synced_printers_manager_;
   ScopedObserver<SyncedPrintersManager, SyncedPrintersManager::Observer>
       synced_printers_manager_observer_;
+  mojo::Remote<chromeos::network_config::mojom::CrosNetworkConfig>
+      remote_cros_network_config_;
+  mojo::Receiver<chromeos::network_config::mojom::CrosNetworkConfigObserver>
+      cros_network_config_observer_receiver_{this};
 
   std::unique_ptr<PrinterDetector> usb_detector_;