Revert "Implement OnNetworkChangeObserver interface on SmbService"

This reverts commit a64eb942.

Reason for revert: <INSERT REASONING HERE>

Original change's description:
> Implement OnNetworkChangeObserver interface on SmbService
> 
> - Implements Net::NetworkChangeNotifier::NetworkChangeObserver to
>   SmbService.
> - Optimizes the workflow of host name resolution by calling on host
>   discovery whenever a network change is discovered, rather than
>   only running host discovery on an error returned by
>   StartReadDirectory.
> 
> Bug: 922273
> Test: manual end to end
> Change-Id: I6544c169fb1aa91ebd7d19fe22d854930ae4a928
> Reviewed-on: https://chromium-review.googlesource.com/c/1464651
> 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@{#634431}

TBR=zentaro@chromium.org,baileyberro@chromium.org,jimmyxgong@chromium.org

Change-Id: Ic731025eafe9fed7c33e6fdf61f56553ba502e81
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 922273
Reviewed-on: https://chromium-review.googlesource.com/c/1482718Reviewed-by: Bailey Berro <baileyberro@chromium.org>
Commit-Queue: jimmy gong <jimmyxgong@chromium.org>
Cr-Commit-Position: refs/heads/master@{#634755}

chrome/browser/chromeos/smb_client/smb_service.cc

@@ -525,7 +525,6 @@ void SmbService::CompleteSetup(
       base::BindRepeating(&SmbService::RequestUpdatedSharePath,
                           base::Unretained(this))));
   RestoreMounts();
-  net::NetworkChangeNotifier::AddNetworkChangeObserver(this);
 }
 
 void SmbService::FireMountCallback(MountResponse callback,
@@ -663,22 +662,6 @@ bool SmbService::ShouldRunHostDiscoveryAgain() const {
          previous_host_discovery_time_ + kHostDiscoveryInterval;
 }
 
-void SmbService::OnNetworkChanged(
-    net::NetworkChangeNotifier::ConnectionType type) {
-  user_manager::User* user =
-      chromeos::ProfileHelper::Get()->GetUserByProfile(profile_);
-
-  if (!user) {
-    // If a network change occurs on the lockscreen, do nothing.
-    return;
-  }
-
-  // Run host discovery to refresh list of cached hosts for subsequent name
-  // resolution attempts.
-  share_finder_->DiscoverHostsInNetwork(base::DoNothing()
-                                        /* HostDiscoveryResponse */);
-}
-
 void SmbService::RecordMountCount() const {
   const std::vector<ProvidedFileSystemInfo> file_systems =
       GetProviderService()->GetProvidedFileSystemInfoList(provider_id_);

chrome/browser/chromeos/smb_client/smb_service.h

@@ -25,7 +25,6 @@
 #include "chrome/browser/profiles/profile.h"
 #include "chromeos/dbus/smb_provider_client.h"
 #include "components/keyed_service/core/keyed_service.h"
-#include "net/base/network_change_notifier.h"
 
 namespace base {
 class FilePath;
@@ -47,7 +46,6 @@ using file_system_provider::Service;
 
 // Creates and manages an smb file system.
 class SmbService : public KeyedService,
-                   public net::NetworkChangeNotifier::NetworkChangeObserver,
                    public base::SupportsWeakPtr<SmbService> {
  public:
   using MountResponse = base::OnceCallback<void(SmbMountResult result)>;
@@ -247,11 +245,6 @@ class SmbService : public KeyedService,
   // false if HostDiscovery was recently run.
   bool ShouldRunHostDiscoveryAgain() const;
 
-  // NetworkChangeNotifier::NetworkChangeObserver override. Runs HostDiscovery
-  // when network detects a change.
-  void OnNetworkChanged(
-      net::NetworkChangeNotifier::ConnectionType type) override;
-
   // Records metrics on the number of SMB mounts a user has.
   void RecordMountCount() const;