Add metrics for smb share authentication method

- Adds a histrogram and metric collection for the authenticaion method
that a user uses.

Bug: chromium:891902
Change-Id: I6f3a9e81ec3983750d006c93fa79b147c83fc98b
Reviewed-on: https://chromium-review.googlesource.com/c/1262971
Commit-Queue: Bailey Berro <baileyberro@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Reviewed-by: Zentaro Kavanagh <zentaro@chromium.org>
Reviewed-by: Ryan Hansberry <hansberry@chromium.org>
Cr-Commit-Position: refs/heads/master@{#598689}

chrome/browser/chromeos/smb_client/smb_service.cc

@@ -62,6 +62,19 @@ bool IsEnabledByFlag() {
 }
 
 // Metric recording functions.
+
+// This enum is used to define the buckets for an enumerated UMA histogram.
+// Hence,
+//   (a) existing enumerated constants should never be deleted or reordered, and
+//   (b) new constants should only be appended at the end of the enumeration.
+enum class AuthMethod {
+  kNoCredentials = 0,
+  kUsernameOnly = 1,
+  kUsernameAndPassword = 2,
+  kSSOKerberos = 3,
+  kMaxValue = kSSOKerberos,
+};
+
 void RecordMountResult(SmbMountResult result) {
   DCHECK_LE(result, SmbMountResult::kMaxValue);
   UMA_HISTOGRAM_ENUMERATION("NativeSmbFileShare.MountResult", result);
@@ -72,6 +85,11 @@ void RecordRemountResult(SmbMountResult result) {
   UMA_HISTOGRAM_ENUMERATION("NativeSmbFileShare.RemountResult", result);
 }
 
+void RecordAuthenticationMethod(AuthMethod method) {
+  DCHECK_LE(method, AuthMethod::kMaxValue);
+  UMA_HISTOGRAM_ENUMERATION("NativeSmbFileShare.AuthenticationMethod", method);
+}
+
 std::unique_ptr<TempFileManager> CreateTempFileManager() {
   return std::make_unique<TempFileManager>();
 }
@@ -134,6 +152,7 @@ void SmbService::CallMount(const file_system_provider::MountOptions& options,
   std::string workgroup;
 
   if (use_chromad_kerberos) {
+    RecordAuthenticationMethod(AuthMethod::kSSOKerberos);
     // Get the user's username and workgroup from their email address to be used
     // for Kerberos authentication.
     user_manager::User* user =
@@ -143,6 +162,15 @@ void SmbService::CallMount(const file_system_provider::MountOptions& options,
       ParseUserPrincipalName(user->GetDisplayEmail(), &username, &workgroup);
     }
   } else {
+    // Record authentication method metrics.
+    if (!username_input.empty() && !password_input.empty()) {
+      RecordAuthenticationMethod(AuthMethod::kUsernameAndPassword);
+    } else if (!username_input.empty()) {
+      RecordAuthenticationMethod(AuthMethod::kUsernameOnly);
+    } else {
+      RecordAuthenticationMethod(AuthMethod::kNoCredentials);
+    }
+
     // Use provided credentials and parse the username into username and
     // workgroup if necessary.
     username = username_input;

tools/metrics/histograms/enums.xml

@@ -33694,6 +33694,13 @@ Called by update_use_counter_css.py.-->
   <int value="10" label="FAILED_TO_FIND_NAMESPACE"/>
 </enum>
 
+<enum name="NativeSmbFileShare_AuthMethod">
+  <int value="0" label="No Credentials."/>
+  <int value="1" label="Username only."/>
+  <int value="2" label="Username and password."/>
+  <int value="3" label="SSO kerberos."/>
+</enum>
+
 <enum name="NativeSmbFileShare_MountResult">
   <int value="0" label="Succeeded"/>
   <int value="1" label="Unknown failure"/>

tools/metrics/histograms/histograms.xml

@@ -50158,6 +50158,15 @@ uploading your change for review.
   </summary>
 </histogram>
 
+<histogram name="NativeSmbFileShare.AuthenticationMethod"
+    enum="NativeSmbFileShare_AuthMethod">
+  <owner>zentaro@chromium.org</owner>
+  <summary>
+    The method used to authenticate to a share. This is called on each attempted
+    mount.
+  </summary>
+</histogram>
+
 <histogram name="NativeSmbFileShare.MountCount">
   <owner>zentaro@chromium.org</owner>
   <summary>