KerberosClient: Add ClearAccounts() method

Exposes the Kerberos daemon's D-Bus method ClearAccounts(). It will be
triggered by Chrome when the kerberos.enabled flag is turned off to
remove all existing accounts. Chrome could also be done by calling
ListAccounts() and then RemoveAccount() multiple times, but that's
rather cumbersome due to the asynchronous nature of each call.

BUG=chromium:952239
TEST=None

Change-Id: I86555386fd58c90ca2644ba05d8b26c7926fe938
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1617454
Commit-Queue: Lutz Justen <ljusten@chromium.org>
Reviewed-by: Dan Erat <derat@chromium.org>
Reviewed-by: Roman Sorokin [CET] <rsorokin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#664285}

chromeos/dbus/kerberos/fake_kerberos_client.cc

@@ -69,6 +69,13 @@ void FakeKerberosClient::RemoveAccount(
   PostResponse(std::move(callback), error);
 }
 
+void FakeKerberosClient::ClearAccounts(
+    const kerberos::ClearAccountsRequest& request,
+    ClearAccountsCallback callback) {
+  accounts_.clear();
+  PostResponse(std::move(callback), kerberos::ERROR_NONE);
+}
+
 void FakeKerberosClient::ListAccounts(
     const kerberos::ListAccountsRequest& request,
     ListAccountsCallback callback) {

chromeos/dbus/kerberos/fake_kerberos_client.h

@@ -26,6 +26,8 @@ class COMPONENT_EXPORT(CHROMEOS_DBUS) FakeKerberosClient
                   AddAccountCallback callback) override;
   void RemoveAccount(const kerberos::RemoveAccountRequest& request,
                      RemoveAccountCallback callback) override;
+  void ClearAccounts(const kerberos::ClearAccountsRequest& request,
+                     ClearAccountsCallback callback) override;
   void ListAccounts(const kerberos::ListAccountsRequest& request,
                     ListAccountsCallback callback) override;
   void SetConfig(const kerberos::SetConfigRequest& request,

chromeos/dbus/kerberos/kerberos_client.cc

@@ -58,6 +58,12 @@ class KerberosClientImpl : public KerberosClient {
                     std::move(callback));
   }
 
+  void ClearAccounts(const kerberos::ClearAccountsRequest& request,
+                     ClearAccountsCallback callback) override {
+    CallProtoMethod(kerberos::kClearAccountsMethod, request,
+                    std::move(callback));
+  }
+
   void ListAccounts(const kerberos::ListAccountsRequest& request,
                     ListAccountsCallback callback) override {
     CallProtoMethod(kerberos::kListAccountsMethod, request,

chromeos/dbus/kerberos/kerberos_client.h

@@ -26,6 +26,8 @@ class COMPONENT_EXPORT(KERBEROS) KerberosClient {
       base::OnceCallback<void(const kerberos::AddAccountResponse& response)>;
   using RemoveAccountCallback =
       base::OnceCallback<void(const kerberos::RemoveAccountResponse& response)>;
+  using ClearAccountsCallback =
+      base::OnceCallback<void(const kerberos::ClearAccountsResponse& response)>;
   using ListAccountsCallback =
       base::OnceCallback<void(const kerberos::ListAccountsResponse& response)>;
   using SetConfigCallback =
@@ -68,6 +70,9 @@ class COMPONENT_EXPORT(KERBEROS) KerberosClient {
   virtual void RemoveAccount(const kerberos::RemoveAccountRequest& request,
                              RemoveAccountCallback callback) = 0;
 
+  virtual void ClearAccounts(const kerberos::ClearAccountsRequest& request,
+                             ClearAccountsCallback callback) = 0;
+
   virtual void ListAccounts(const kerberos::ListAccountsRequest& request,
                             ListAccountsCallback callback) = 0;