Add TryResolveUrl to SmbShareFinder

- Introduces a method that attempts to resolve an SmbUrl and
  returns whether it was able to.
- This new method will be used to determine if a hostname was
  resolved during dynamic hostname resolution.

Bug: 922273
Test: compiles
Change-Id: I9c15a2ccfd07cd8f4f8c888c3358c42b74253984
Reviewed-on: https://chromium-review.googlesource.com/c/1444598
Commit-Queue: jimmy gong <jimmyxgong@chromium.org>
Reviewed-by: Bailey Berro <baileyberro@chromium.org>
Auto-Submit: jimmy gong <jimmyxgong@chromium.org>
Cr-Commit-Position: refs/heads/master@{#630602}

chrome/browser/chromeos/smb_client/smb_service.cc

@@ -261,10 +261,10 @@ void SmbService::CallMount(const file_system_provider::MountOptions& options,
 
   // If using kerberos, the hostname should not be resolved since kerberos
   // service tickets are keyed on hosname.
-  const base::FilePath mount_path =
-      use_chromad_kerberos
-          ? base::FilePath(parsed_url.ToString())
-          : base::FilePath(share_finder_->GetResolvedUrl(parsed_url));
+  const std::string url = use_chromad_kerberos
+                              ? parsed_url.ToString()
+                              : share_finder_->GetResolvedUrl(parsed_url);
+  const base::FilePath mount_path(url);
 
   GetSmbProviderClient()->Mount(
       mount_path, IsNTLMAuthenticationEnabled(), workgroup, username,

chrome/browser/chromeos/smb_client/smb_share_finder.cc

@@ -52,13 +52,21 @@ std::string SmbShareFinder::GetResolvedUrl(const SmbUrl& url) const {
   DCHECK(url.IsValid());
 
   const std::string ip_address = scanner_.ResolveHost(url.GetHost());
-  if (ip_address.empty()) {
+  // Return the original URL if the resolved host cannot be found or if there is
+  // no change in the resolved IP address.
+  if (ip_address.empty() || ip_address == url.GetHost()) {
     return url.ToString();
   }
 
   return url.ReplaceHost(ip_address);
 }
 
+bool SmbShareFinder::TryResolveUrl(const SmbUrl& url,
+                                   std::string* updated_url) const {
+  *updated_url = GetResolvedUrl(url);
+  return *updated_url != url.ToString();
+}
+
 void SmbShareFinder::OnHostsDiscovered(HostDiscoveryResponse discovery_callback,
                                        bool success,
                                        const HostMap& hosts) {

chrome/browser/chromeos/smb_client/smb_share_finder.h

@@ -58,6 +58,11 @@ class SmbShareFinder : public base::SupportsWeakPtr<SmbShareFinder> {
   // otherwise returns ToString of |url|.
   std::string GetResolvedUrl(const SmbUrl& url) const;
 
+  // Attempts to resolve |url|. If able to resolve |url|, returns true and sets
+  // |resolved_url| the the resolved url. If unable, returns false and sets
+  // |resolved_url| to ToString of |url|.
+  bool TryResolveUrl(const SmbUrl& url, std::string* updated_url) const;
+
  private:
   // Handles the response from discovering hosts in the network.
   void OnHostsDiscovered(HostDiscoveryResponse discovery_callback,