Check NetBios Discovery policy when adding host locators

This change enforces the NetBiosShareDiscoveryEnabled policy. If enforced,
no NetBios discovery will be set up or performed when by the SmbService.

Bug: 757625
Change-Id: I8bcd8d049dc597db208f9c38fae5a17b8069dd28
Reviewed-on: https://chromium-review.googlesource.com/1185405
Commit-Queue: Bailey Berro <baileyberro@chromium.org>
Reviewed-by: Zentaro Kavanagh <zentaro@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585516}

chrome/browser/chromeos/smb_client/smb_service.cc

@@ -320,7 +320,11 @@ void SmbService::FireMountCallback(MountResponse callback,
 
 void SmbService::RegisterHostLocators() {
   SetUpMdnsHostLocator();
-  SetUpNetBiosHostLocator();
+  if (IsNetBiosDiscoveryEnabled()) {
+    SetUpNetBiosHostLocator();
+  } else {
+    LOG(WARNING) << "SmbService: NetBios discovery disabled.";
+  }
 }
 
 void SmbService::SetUpMdnsHostLocator() {
@@ -342,6 +346,10 @@ bool SmbService::IsAllowedByPolicy() const {
   return profile_->GetPrefs()->GetBoolean(prefs::kNetworkFileSharesAllowed);
 }
 
+bool SmbService::IsNetBiosDiscoveryEnabled() const {
+  return profile_->GetPrefs()->GetBoolean(prefs::kNetBiosShareDiscoveryEnabled);
+}
+
 void SmbService::RecordMountCount() const {
   const std::vector<ProvidedFileSystemInfo> file_systems =
       GetProviderService()->GetProvidedFileSystemInfoList(provider_id_);

chrome/browser/chromeos/smb_client/smb_service.h

@@ -138,6 +138,9 @@ class SmbService : public KeyedService,
   // Whether Network File Shares are allowed to be used. Controlled via policy.
   bool IsAllowedByPolicy() const;
 
+  // Whether NetBios discovery should be used. Controlled via policy.
+  bool IsNetBiosDiscoveryEnabled() const;
+
   // Records metrics on the number of SMB mounts a user has.
   void RecordMountCount() const;