Add discovery and share callback vectors to SmbShareFinder

- Adds vectors for both discovery and share callbacks.
- Solves the race condition in which multiple
  dialogs of "Add Smb Share" would use a shared instance of each
  HostLocator.
- If a SmbShareFinder::GatherSharesInNetwork call comes in when one is
  already running, the callbacks are stored and run when the original
  GatherSharesInNetwork call finishes.
- Adds additional unit test to reflect on the changes.

Bug: chromium:892287
Test: end-to-end
Change-Id: I9551532dc08fd9338803786bdd89f0398f4ce7db
Reviewed-on: https://chromium-review.googlesource.com/c/1336435Reviewed-by: Bailey Berro <baileyberro@chromium.org>
Reviewed-by: Zentaro Kavanagh <zentaro@chromium.org>
Commit-Queue: jimmy gong <jimmyxgong@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611409}

chrome/browser/chromeos/smb_client/discovery/in_memory_host_locator.cc

@@ -11,6 +11,8 @@ namespace chromeos {
 namespace smb_client {
 
 InMemoryHostLocator::InMemoryHostLocator() = default;
+InMemoryHostLocator::InMemoryHostLocator(bool should_run_synchronously)
+    : should_run_synchronously_(should_run_synchronously) {}
 InMemoryHostLocator::~InMemoryHostLocator() = default;
 
 void InMemoryHostLocator::AddHost(const Hostname& hostname,
@@ -29,7 +31,17 @@ void InMemoryHostLocator::RemoveHost(const Hostname& hostname) {
 }
 
 void InMemoryHostLocator::FindHosts(FindHostsCallback callback) {
-  std::move(callback).Run(true /* success */, host_map_);
+  if (should_run_synchronously_) {
+    std::move(callback).Run(true /* success */, host_map_);
+  } else {
+    stored_callback_ = std::move(callback);
+  }
+}
+
+void InMemoryHostLocator::RunCallback() {
+  DCHECK(!should_run_synchronously_);
+
+  std::move(stored_callback_).Run(true /* success */, host_map_);
 }
 
 }  // namespace smb_client

chrome/browser/chromeos/smb_client/discovery/in_memory_host_locator.h

@@ -15,6 +15,8 @@ namespace smb_client {
 class InMemoryHostLocator : public HostLocator {
  public:
   InMemoryHostLocator();
+  explicit InMemoryHostLocator(bool should_run_synchronously);
+
   ~InMemoryHostLocator() override;
 
   // Adds host with |hostname| and |address| to host_map_.
@@ -29,8 +31,13 @@ class InMemoryHostLocator : public HostLocator {
   // HostLocator override.
   void FindHosts(FindHostsCallback callback) override;
 
+  // Runs the callback, |stored_callback_|.
+  void RunCallback();
+
  private:
   HostMap host_map_;
+  FindHostsCallback stored_callback_;
+  bool should_run_synchronously_ = true;
 
   DISALLOW_COPY_AND_ASSIGN(InMemoryHostLocator);
 };

chrome/browser/chromeos/smb_client/discovery/network_scanner.cc

@@ -37,12 +37,16 @@ NetworkScanner::NetworkScanner() = default;
 NetworkScanner::~NetworkScanner() = default;
 
 void NetworkScanner::FindHostsInNetwork(FindHostsCallback callback) {
+  DCHECK(!running_);
+
   if (locators_.empty()) {
     // Fire the callback immediately if there are no registered HostLocators.
     std::move(callback).Run(false /* success */, HostMap());
     return;
   }
 
+  running_ = true;
+
   const uint32_t request_id = AddNewRequest(std::move(callback));
   for (const auto& locator : locators_) {
     locator->FindHosts(
@@ -118,6 +122,7 @@ void NetworkScanner::FireCallbackIfFinished(uint32_t request_id) {
     found_hosts_ = std::move(info.hosts_found);
     find_hosts_returned_ = true;
 
+    running_ = false;
     std::move(info.callback).Run(true /* success */, found_hosts_);
   }
 }

chrome/browser/chromeos/smb_client/discovery/network_scanner.h

@@ -90,6 +90,12 @@ class NetworkScanner : public base::SupportsWeakPtr<NetworkScanner> {
   // regardless if any hosts are found.
   bool find_hosts_returned_ = false;
 
+  // True if FindHostsInNetwork() has been called and is waiting for
+  // FindHostsCallback to be invoked. This is to prevent multiple calls of
+  // FindHostsInNetwork() from concurrently executing. Used only for DCHECKing
+  // if FindHostsInNetwork() is already running.
+  bool running_ = false;
+
   DISALLOW_COPY_AND_ASSIGN(NetworkScanner);
 };
 

chrome/browser/chromeos/smb_client/smb_share_finder.cc

@@ -18,10 +18,23 @@ SmbShareFinder::~SmbShareFinder() = default;
 
 void SmbShareFinder::GatherSharesInNetwork(
     HostDiscoveryResponse discovery_callback,
-    GatherSharesResponse shares_callback) {
-  scanner_.FindHostsInNetwork(base::BindOnce(
-      &SmbShareFinder::OnHostsFound, AsWeakPtr(), std::move(discovery_callback),
-      std::move(shares_callback)));
+    GatherSharesInNetworkResponse shares_callback) {
+  const bool should_start_discovery = share_callbacks_.empty();
+
+  if (discovery_callbacks_.empty() && !should_start_discovery) {
+    // Host discovery completed but shares callback is still in progress.
+    std::move(discovery_callback).Run();
+    InsertShareCallback(std::move(shares_callback));
+  } else {
+    // Either GatherSharesInNetwork has not been called yet or it has and
+    // discovery has not yet finished.
+    InsertDiscoveryAndShareCallbacks(std::move(discovery_callback),
+                                     std::move(shares_callback));
+  }
+  if (should_start_discovery) {
+    scanner_.FindHostsInNetwork(
+        base::BindOnce(&SmbShareFinder::OnHostsFound, AsWeakPtr()));
+  }
 }
 
 void SmbShareFinder::DiscoverHostsInNetwork(
@@ -52,55 +65,89 @@ void SmbShareFinder::OnHostsDiscovered(HostDiscoveryResponse discovery_callback,
   std::move(discovery_callback).Run();
 }
 
-void SmbShareFinder::OnHostsFound(HostDiscoveryResponse discovery_callback,
-                                  GatherSharesResponse shares_callback,
-                                  bool success,
-                                  const HostMap& hosts) {
-  std::move(discovery_callback).Run();
+void SmbShareFinder::OnHostsFound(bool success, const HostMap& hosts) {
+  DCHECK_EQ(0u, host_counter_);
+
+  RunDiscoveryCallbacks();
+
   if (!success) {
     LOG(ERROR) << "SmbShareFinder failed to find hosts";
-    shares_callback.Run(std::vector<SmbUrl>());
+    RunEmptySharesCallbacks();
     return;
   }
 
   if (hosts.empty()) {
-    shares_callback.Run(std::vector<SmbUrl>());
+    RunEmptySharesCallbacks();
     return;
   }
 
+  host_counter_ = hosts.size();
   for (const auto& host : hosts) {
     const std::string& host_name = host.first;
     const std::string& resolved_address = host.second;
     const base::FilePath server_url(kSmbSchemePrefix + resolved_address);
 
     client_->GetShares(
-        server_url, base::BindOnce(&SmbShareFinder::OnSharesFound, AsWeakPtr(),
-                                   host_name, shares_callback));
+        server_url,
+        base::BindOnce(&SmbShareFinder::OnSharesFound, AsWeakPtr(), host_name));
   }
 }
 
 void SmbShareFinder::OnSharesFound(
     const std::string& host_name,
-    GatherSharesResponse shares_callback,
     smbprovider::ErrorType error,
     const smbprovider::DirectoryEntryListProto& entries) {
+  DCHECK_GT(host_counter_, 0u);
+  --host_counter_;
+
   if (error != smbprovider::ErrorType::ERROR_OK) {
     LOG(ERROR) << "Error finding shares: " << error;
-    shares_callback.Run(std::vector<SmbUrl>());
     return;
   }
 
-  std::vector<SmbUrl> shares;
   for (const smbprovider::DirectoryEntryProto& entry : entries.entries()) {
     SmbUrl url(kSmbSchemePrefix + host_name + "/" + entry.name());
     if (url.IsValid()) {
-      shares.push_back(std::move(url));
+      shares_.push_back(std::move(url));
     } else {
       LOG(WARNING) << "URL found is not valid";
     }
   }
 
-  shares_callback.Run(shares);
+  if (host_counter_ == 0) {
+    RunSharesCallbacks(shares_);
+  }
+}
+
+void SmbShareFinder::RunDiscoveryCallbacks() {
+  for (auto& callback : discovery_callbacks_) {
+    std::move(callback).Run();
+  }
+  discovery_callbacks_.clear();
+}
+
+void SmbShareFinder::RunSharesCallbacks(const std::vector<SmbUrl>& shares) {
+  for (auto& share_callback : share_callbacks_) {
+    std::move(share_callback).Run(shares);
+  }
+  share_callbacks_.clear();
+  shares_.clear();
+}
+
+void SmbShareFinder::RunEmptySharesCallbacks() {
+  RunSharesCallbacks(std::vector<SmbUrl>());
+}
+
+void SmbShareFinder::InsertDiscoveryAndShareCallbacks(
+    HostDiscoveryResponse discovery_callback,
+    GatherSharesInNetworkResponse share_callback) {
+  discovery_callbacks_.push_back(std::move(discovery_callback));
+  share_callbacks_.push_back(std::move(share_callback));
+}
+
+void SmbShareFinder::InsertShareCallback(
+    GatherSharesInNetworkResponse share_callback) {
+  share_callbacks_.push_back(std::move(share_callback));
 }
 
 }  // namespace smb_client

chrome/browser/chromeos/smb_client/smb_share_finder.h

@@ -23,6 +23,11 @@ namespace smb_client {
 using GatherSharesResponse =
     base::RepeatingCallback<void(const std::vector<SmbUrl>& shares_gathered)>;
 
+// The callback that will be passed to GatherSharesInNetwork. Used to implicitly
+// convert GatherSharesResponse to a OnceCallback.
+using GatherSharesInNetworkResponse =
+    base::OnceCallback<void(const std::vector<SmbUrl>& shares_gathered)>;
+
 // The callback run to indicate the scan for hosts on the network is complete.
 using HostDiscoveryResponse = base::OnceClosure;
 
@@ -35,10 +40,11 @@ class SmbShareFinder : public base::SupportsWeakPtr<SmbShareFinder> {
 
   // Gathers the hosts in the network using |scanner_| and gets the shares for
   // each of the hosts found. |discovery_callback| runs once when host
-  // disovery is complete. |shares_callback| runs once per host and will contain
-  // the paths to the shares found (e.g. "smb://host/share").
+  // disovery is complete. |shares_callback| only runs once when all entries
+  // from hosts are stored to |shares| and will contain the paths to the shares
+  // found (e.g. "smb://host/share").
   void GatherSharesInNetwork(HostDiscoveryResponse discovery_callback,
-                             GatherSharesResponse shares_callback);
+                             GatherSharesInNetworkResponse shares_callback);
 
   // Gathers the hosts in the network using |scanner_|. Runs
   // |discovery_callback| upon completion. No data is returned to the caller,
@@ -59,21 +65,43 @@ class SmbShareFinder : public base::SupportsWeakPtr<SmbShareFinder> {
                          const HostMap& hosts);
 
   // Handles the response from finding hosts in the network.
-  void OnHostsFound(HostDiscoveryResponse discovery_callback,
-                    GatherSharesResponse shares_callback,
-                    bool success,
-                    const HostMap& hosts);
+  void OnHostsFound(bool success, const HostMap& hosts);
 
   // Handles the response from getting shares for a given host.
   void OnSharesFound(const std::string& host_name,
-                     GatherSharesResponse shares_callback,
                      smbprovider::ErrorType error,
                      const smbprovider::DirectoryEntryListProto& entries);
 
+  // Executes all the DiscoveryCallbacks inside |discovery_callbacks_|.
+  void RunDiscoveryCallbacks();
+
+  // Executes all the SharesCallback inside |shares_callback_|.
+  void RunSharesCallbacks(const std::vector<SmbUrl>& shares);
+
+  // Executes all the SharesCallback inside |shares_callback_| with an empty
+  // vector of SmbUrl.
+  void RunEmptySharesCallbacks();
+
+  // Inserts HostDiscoveryResponse in |discovery_callbacks_| and inserts
+  // GatherSharesInNetworkResponse in |shares_callbacks_|.
+  void InsertDiscoveryAndShareCallbacks(
+      HostDiscoveryResponse discovery_callback,
+      GatherSharesInNetworkResponse shares_callback);
+
+  // Inserts |shares_callback| to |share_callbacks_|.
+  void InsertShareCallback(GatherSharesInNetworkResponse shares_callback);
+
   NetworkScanner scanner_;
 
   SmbProviderClient* client_;  // Not owned.
 
+  uint32_t host_counter_ = 0u;
+
+  std::vector<HostDiscoveryResponse> discovery_callbacks_;
+  std::vector<GatherSharesInNetworkResponse> share_callbacks_;
+
+  std::vector<SmbUrl> shares_;
+
   DISALLOW_COPY_AND_ASSIGN(SmbShareFinder);
 };
 

chrome/browser/chromeos/smb_client/smb_share_finder_unittest.cc

@@ -31,17 +31,12 @@ constexpr char kDefaultResolvedUrl[] = "smb://1.2.3.4";
 class SmbShareFinderTest : public testing::Test {
  public:
   SmbShareFinderTest() {
-    auto host_locator = std::make_unique<InMemoryHostLocator>();
-    host_locator_ = host_locator.get();
-
-    fake_client_ = std::make_unique<FakeSmbProviderClient>();
-    share_finder_ = std::make_unique<SmbShareFinder>(fake_client_.get());
-
-    share_finder_->RegisterHostLocator(std::move(host_locator));
+    SetupShareFinderTest(true /* should_run_synchronously */);
   }
 
   ~SmbShareFinderTest() override = default;
 
+ protected:
   void TearDown() override { fake_client_->ClearShares(); }
 
   // Adds host with |hostname| and |address| as the resolved url.
@@ -67,23 +62,39 @@ class SmbShareFinderTest : public testing::Test {
   }
 
   // Helper function when expecting shares to be found in the network.
-  void ExpectSharesFound() {
+  void StartDiscoveryWhileExpectingSharesFound() {
     share_finder_->GatherSharesInNetwork(
         base::BindOnce(&SmbShareFinderTest::HostsDiscoveredCallback,
                        base::Unretained(this)),
-        base::BindRepeating(&SmbShareFinderTest::SharesFoundCallback,
-                            base::Unretained(this)));
+        base::BindOnce(&SmbShareFinderTest::SharesFoundCallback,
+                       base::Unretained(this)));
     EXPECT_TRUE(discovery_callback_called_);
   }
 
   // Helper function when expecting no shares to be found in the network.
   void ExpectNoSharesFound() {
+    StartDiscoveryWhileExpectingEmptyShares();
+    EXPECT_TRUE(discovery_callback_called_);
+  }
+
+  // Helper function to call SmbShareFinder::GatherSharesInNetwork. Asserts that
+  // there are no shares discovered from the EmptySharesCallback.
+  void StartDiscoveryWhileExpectingEmptyShares() {
     share_finder_->GatherSharesInNetwork(
         base::BindOnce(&SmbShareFinderTest::HostsDiscoveredCallback,
                        base::Unretained(this)),
-        base::BindRepeating(&SmbShareFinderTest::EmptySharesCallback,
-                            base::Unretained(this)));
-    EXPECT_TRUE(discovery_callback_called_);
+        base::BindOnce(&SmbShareFinderTest::EmptySharesCallback,
+                       base::Unretained(this)));
+  }
+
+  // Helper function to call SmbShareFinder::GatherSharesInNetwork. Asserts that
+  // shares are found, but does not remove them.
+  void StartDiscoveryWhileGatheringShares() {
+    share_finder_->GatherSharesInNetwork(
+        base::BindOnce(&SmbShareFinderTest::HostsDiscoveredCallback,
+                       base::Unretained(this)),
+        base::BindOnce(&SmbShareFinderTest::SharesFoundSizeCallback,
+                       base::Unretained(this)));
   }
 
   // Helper function that expects expected_shares_ to be empty.
@@ -94,8 +105,33 @@ class SmbShareFinderTest : public testing::Test {
     EXPECT_EQ(expected, share_finder_->GetResolvedUrl(url));
   }
 
+  void ExpectDiscoveryCalled(int32_t expected) {
+    EXPECT_EQ(expected, discovery_callback_counter_);
+  }
+
+  void FinishHostDiscoveryOnHostLocator() { host_locator_->RunCallback(); }
+
+  void FinishShareDiscoveryOnSmbProviderClient() {
+    fake_client_->RunStoredReadDirCallback();
+  }
+
+  void SetupShareFinderTest(bool should_run_synchronously) {
+    auto host_locator =
+        std::make_unique<InMemoryHostLocator>(should_run_synchronously);
+    host_locator_ = host_locator.get();
+
+    fake_client_ =
+        std::make_unique<FakeSmbProviderClient>(should_run_synchronously);
+    share_finder_ = std::make_unique<SmbShareFinder>(fake_client_.get());
+
+    share_finder_->RegisterHostLocator(std::move(host_locator));
+  }
+
  private:
-  void HostsDiscoveredCallback() { discovery_callback_called_ = true; }
+  void HostsDiscoveredCallback() {
+    discovery_callback_called_ = true;
+    ++discovery_callback_counter_;
+  }
 
   // Removes shares discovered from |expected_shares_|.
   void SharesFoundCallback(const std::vector<SmbUrl>& shares_found) {
@@ -106,6 +142,10 @@ class SmbShareFinderTest : public testing::Test {
     }
   }
 
+  void SharesFoundSizeCallback(const std::vector<SmbUrl>& shares_found) {
+    EXPECT_GE(shares_found.size(), 0u);
+  }
+
   void EmptySharesCallback(const std::vector<SmbUrl>& shares_found) {
     EXPECT_EQ(0u, shares_found.size());
   }
@@ -115,6 +155,8 @@ class SmbShareFinderTest : public testing::Test {
   // Keeps track of expected shares across multiple hosts.
   std::set<std::string> expected_shares_;
 
+  int32_t discovery_callback_counter_ = 0;
+
   InMemoryHostLocator* host_locator_;
   std::unique_ptr<FakeSmbProviderClient> fake_client_;
   std::unique_ptr<SmbShareFinder> share_finder_;
@@ -142,7 +184,7 @@ TEST_F(SmbShareFinderTest, SharesFoundWithSingleHost) {
   AddShareToDefaultHost("share1");
   AddShareToDefaultHost("share2");
 
-  ExpectSharesFound();
+  StartDiscoveryWhileExpectingSharesFound();
   ExpectAllSharesHaveBeenFound();
 }
 
@@ -158,7 +200,7 @@ TEST_F(SmbShareFinderTest, SharesFoundWithMultipleHosts) {
   AddHost(host2, address2);
   AddShare(resolved_server_url2, server_url2, share2);
 
-  ExpectSharesFound();
+  StartDiscoveryWhileExpectingSharesFound();
   ExpectAllSharesHaveBeenFound();
 }
 
@@ -168,7 +210,7 @@ TEST_F(SmbShareFinderTest, SharesFoundOnOneHostWithMultipleHosts) {
 
   AddHost("host2", "4.5.6.7");
 
-  ExpectSharesFound();
+  StartDiscoveryWhileExpectingSharesFound();
   ExpectAllSharesHaveBeenFound();
 }
 
@@ -177,7 +219,7 @@ TEST_F(SmbShareFinderTest, ResolvesHostToOriginalUrlIfNoHostFound) {
   SmbUrl smb_url(url);
 
   // Trigger the NetworkScanner to scan the network with its HostLocators.
-  ExpectSharesFound();
+  StartDiscoveryWhileExpectingSharesFound();
 
   ExpectResolvedHost(smb_url, url);
 }
@@ -186,7 +228,7 @@ TEST_F(SmbShareFinderTest, ResolvesHost) {
   AddDefaultHost();
 
   // Trigger the NetworkScanner to scan the network with its HostLocators.
-  ExpectSharesFound();
+  StartDiscoveryWhileExpectingSharesFound();
 
   SmbUrl url(std::string(kDefaultUrl) + "share");
   ExpectResolvedHost(url, std::string(kDefaultResolvedUrl) + "/share");
@@ -197,11 +239,55 @@ TEST_F(SmbShareFinderTest, ResolvesHostWithMultipleHosts) {
   AddHost("host2", "4.5.6.7");
 
   // Trigger the NetworkScanner to scan the network with its HostLocators.
-  ExpectSharesFound();
+  StartDiscoveryWhileExpectingSharesFound();
 
   SmbUrl url("smb://host2/share");
   ExpectResolvedHost(url, "smb://4.5.6.7/share");
 }
 
+TEST_F(SmbShareFinderTest, TestNonEmptyDiscoveryWithNonEmptyShareCallback) {
+  SetupShareFinderTest(false /* should_run_synchronoulsy */);
+
+  AddDefaultHost();
+
+  // Start discovery twice before host discovery is compeleted.
+  StartDiscoveryWhileExpectingEmptyShares();
+  StartDiscoveryWhileExpectingEmptyShares();
+
+  // Assert discovery callback has not been called.
+  ExpectDiscoveryCalled(0 /* expected */);
+
+  FinishHostDiscoveryOnHostLocator();
+
+  ExpectDiscoveryCalled(2 /* expected */);
+}
+
+TEST_F(SmbShareFinderTest, TestEmptyDiscoveryWithNonEmptyShareCallback) {
+  SetupShareFinderTest(false /* should_run_synchronoulsy */);
+
+  AddDefaultHost();
+  AddShareToDefaultHost("share1");
+  AddShareToDefaultHost("share2");
+
+  // Makes call to start discovery once. Share discovery will not run and be in
+  // a pending state.
+  StartDiscoveryWhileGatheringShares();
+
+  FinishHostDiscoveryOnHostLocator();
+
+  ExpectDiscoveryCalled(1 /* expected */);
+
+  // Host discovery will complete immediately while share discoveries will
+  // remain pending.
+  StartDiscoveryWhileExpectingSharesFound();
+
+  ExpectDiscoveryCalled(2 /* expected */);
+
+  // Run shares callback.
+  FinishShareDiscoveryOnSmbProviderClient();
+
+  ExpectAllSharesHaveBeenFound();
+}
+
 }  // namespace smb_client
 }  // namespace chromeos

chromeos/dbus/fake_smb_provider_client.cc

@@ -30,6 +30,9 @@ void AddDirectoryEntryToList(smbprovider::DirectoryEntryListProto* entry_list,
 
 FakeSmbProviderClient::FakeSmbProviderClient() {}
 
+FakeSmbProviderClient::FakeSmbProviderClient(bool should_run_synchronously)
+    : should_run_synchronously_(should_run_synchronously) {}
+
 FakeSmbProviderClient::~FakeSmbProviderClient() {}
 
 void FakeSmbProviderClient::AddNetBiosPacketParsingForTesting(
@@ -184,7 +187,12 @@ void FakeSmbProviderClient::GetShares(const base::FilePath& server_url,
     AddDirectoryEntryToList(&entry_list, share);
   }
 
-  std::move(callback).Run(smbprovider::ERROR_OK, entry_list);
+  if (should_run_synchronously_) {
+    std::move(callback).Run(smbprovider::ERROR_OK, entry_list);
+  } else {
+    stored_readdir_callback_ =
+        base::BindOnce(std::move(callback), smbprovider::ERROR_OK, entry_list);
+  }
 }
 
 void FakeSmbProviderClient::SetupKerberos(const std::string& account_id,
@@ -255,4 +263,8 @@ void FakeSmbProviderClient::ClearShares() {
   shares_.clear();
 }
 
+void FakeSmbProviderClient::RunStoredReadDirCallback() {
+  std::move(stored_readdir_callback_).Run();
+}
+
 }  // namespace chromeos

chromeos/dbus/fake_smb_provider_client.h

@@ -17,6 +17,7 @@ namespace chromeos {
 class CHROMEOS_EXPORT FakeSmbProviderClient : public SmbProviderClient {
  public:
   FakeSmbProviderClient();
+  explicit FakeSmbProviderClient(bool should_run_synchronously);
   ~FakeSmbProviderClient() override;
 
   // Adds an entry in the |netbios_parse_results_| map for <packetid,
@@ -135,7 +136,15 @@ class CHROMEOS_EXPORT FakeSmbProviderClient : public SmbProviderClient {
   // Clears |shares_|.
   void ClearShares();
 
+  // Runs |stored_callback_|.
+  void RunStoredReadDirCallback();
+
  private:
+  // Controls whether |stored_readdir_callback_| should run synchronously.
+  bool should_run_synchronously_ = true;
+
+  base::OnceClosure stored_readdir_callback_;
+
   std::map<uint8_t, std::vector<std::string>> netbios_parse_results_;
 
   // Mapping of a server url to its shares.