diff --git a/internal/platform/implementation/account_manager.h b/internal/platform/implementation/account_manager.h
index bf2e20f6..c462b45d 100644
--- a/internal/platform/implementation/account_manager.h
+++ b/internal/platform/implementation/account_manager.h
@@ -55,7 +55,7 @@ class AccountManager {
   // Gets current active account. If no login user, return std::nullopt.
   virtual std::optional<Account> GetCurrentAccount() = 0;
 
-  // Initializes the login process for a Google account.
+  // Initializes the login process for a Google account from 1P client.
   // |login_success_callback| is called when the login succeeded. Account
   // information is passed to callback.
   // |login_failure_callback| is called when the login fails.
@@ -63,6 +63,17 @@ class AccountManager {
       absl::AnyInvocable<void(Account)> login_success_callback,
       absl::AnyInvocable<void(absl::Status)> login_failure_callback) = 0;
 
+  // Initializes the login process for a Google account from an oauth client.
+  // |client_id| GCP client_id of the client
+  // |client_secret| GCP client_secret of the client
+  // |login_success_callback| is called when the login succeeded. Account
+  // information is passed to callback.
+  // |login_failure_callback| is called when the login fails.
+  virtual void Login(
+      absl::string_view client_id, absl::string_view client_secret,
+      absl::AnyInvocable<void(Account)> login_success_callback,
+      absl::AnyInvocable<void(absl::Status)> login_failure_callback) = 0;
+
   // Logs out current active account. |logout_callback| is called when logout is
   // completed.
   virtual void Logout(
diff --git a/internal/test/fake_account_manager.cc b/internal/test/fake_account_manager.cc
index 2ee7a3d3..dfb98f90 100644
--- a/internal/test/fake_account_manager.cc
+++ b/internal/test/fake_account_manager.cc
@@ -46,6 +46,22 @@ void FakeAccountManager::Login(
   login_failure_callback(absl::InternalError("No account."));
 }
 
+void FakeAccountManager::Login(
+    absl::string_view client_id, absl::string_view client_secret,
+    absl::AnyInvocable<void(Account)> login_success_callback,
+    absl::AnyInvocable<void(absl::Status)> login_failure_callback) {
+  if (account_.has_value()) {
+    UpdateCurrentUser(account_->id);
+    NotifyLogin(account_->id);
+    // Invoke callback after all operations have been performed since test cases
+    // may rely on the callback for synchronization.
+    login_success_callback(*account_);
+    return;
+  }
+
+  login_failure_callback(absl::InternalError("No account."));
+}
+
 void FakeAccountManager::Logout(
     absl::AnyInvocable<void(absl::Status)> logout_callback) {
   if (is_logout_success_) {
diff --git a/internal/test/fake_account_manager.h b/internal/test/fake_account_manager.h
index 4da65b73..d53fa0c2 100644
--- a/internal/test/fake_account_manager.h
+++ b/internal/test/fake_account_manager.h
@@ -39,6 +39,11 @@ class FakeAccountManager : public AccountManager {
       absl::AnyInvocable<void(Account)> login_success_callback,
       absl::AnyInvocable<void(absl::Status)> login_failure_callback) override;
 
+  void Login(
+      absl::string_view client_id, absl::string_view client_secret,
+      absl::AnyInvocable<void(Account)> login_success_callback,
+      absl::AnyInvocable<void(absl::Status)> login_failure_callback) override;
+
   void Logout(absl::AnyInvocable<void(absl::Status)> logout_callback) override;
 
   bool GetAccessToken(
diff --git a/internal/test/mock_account_manager.h b/internal/test/mock_account_manager.h
index 49746c25..41765c01 100644
--- a/internal/test/mock_account_manager.h
+++ b/internal/test/mock_account_manager.h
@@ -32,6 +32,11 @@ class MockAccountManager : public AccountManager {
               (absl::AnyInvocable<void(Account)> login_success_callback,
                absl::AnyInvocable<void(absl::Status)> login_failure_callback),
               (override));
+  MOCK_METHOD(void, Login,
+              (absl::string_view client_id, absl::string_view client_secret,
+               absl::AnyInvocable<void(Account)> login_success_callback,
+               absl::AnyInvocable<void(absl::Status)> login_failure_callback),
+              (override));
   MOCK_METHOD(void, Logout,
               (absl::AnyInvocable<void(absl::Status)> logout_callback),
               (override));
diff --git a/sharing/certificates/nearby_share_certificate_manager_impl_test.cc b/sharing/certificates/nearby_share_certificate_manager_impl_test.cc
index feb6fcd4..da269b03 100644
--- a/sharing/certificates/nearby_share_certificate_manager_impl_test.cc
+++ b/sharing/certificates/nearby_share_certificate_manager_impl_test.cc
@@ -117,8 +117,9 @@ class NearbyShareCertificateManagerImplTest
 
     fake_account_manager_.SetAccount(account);
 
-    fake_account_manager_.Login([](AccountManager::Account account) {},
-                                [](absl::Status status) {});
+    fake_account_manager_.Login(
+        "test_client_id", "test_client_secret",
+        [](AccountManager::Account account) {}, [](absl::Status status) {});
 
     NearbyShareSchedulerFactory::SetFactoryForTesting(&scheduler_factory_);
     NearbyShareCertificateStorageImpl::Factory::SetFactoryForTesting(
@@ -511,10 +512,10 @@ TEST_F(NearbyShareCertificateManagerImplTest,
   FastForward(GetNearbyShareTestNotBefore() +
               kNearbyShareCertificateValidityPeriod * 0.5 - Now());
 
-  std::optional<NearbyShareEncryptedMetadataKey> encrypted_metadata_key_everyone
-      =
-      cert_manager_->EncryptPrivateCertificateMetadataKey(
-          DeviceVisibility::DEVICE_VISIBILITY_EVERYONE);
+  std::optional<NearbyShareEncryptedMetadataKey>
+      encrypted_metadata_key_everyone =
+          cert_manager_->EncryptPrivateCertificateMetadataKey(
+              DeviceVisibility::DEVICE_VISIBILITY_EVERYONE);
   EXPECT_EQ(GetNearbyShareTestEncryptedMetadataKey().encrypted_key(),
             encrypted_metadata_key_everyone->encrypted_key());
   EXPECT_EQ(GetNearbyShareTestEncryptedMetadataKey().salt(),
diff --git a/sharing/nearby_sharing_service_impl_test.cc b/sharing/nearby_sharing_service_impl_test.cc
index 581e5cf3..6c0a186f 100644
--- a/sharing/nearby_sharing_service_impl_test.cc
+++ b/sharing/nearby_sharing_service_impl_test.cc
@@ -2174,6 +2174,7 @@ TEST_F(NearbySharingServiceImplTest, ValidateLoginStateWhenSettingVisibility) {
   absl::Notification login_notification;
   account_manager().SetAccount(account);
   service_->GetAccountManager()->Login(
+      "test_client_id", "test_client_secret",
       [&](AccountManager::Account account) {
         EXPECT_EQ(account.id, kTestAccountId);
         login_notification.Notify();
@@ -4467,6 +4468,7 @@ TEST_F(NearbySharingServiceImplTest, ObserveAccountLoginAndLogout) {
   account.id = kTestAccountId;
   account_manager().SetAccount(account);
   service_->GetAccountManager()->Login(
+      "test_client_id", "test_client_secret",
       [&](AccountManager::Account account) {
         EXPECT_EQ(account.id, kTestAccountId);
         notification.Notify();
@@ -4499,6 +4501,7 @@ TEST_F(NearbySharingServiceImplTest, LoginAndLogoutShouldResetSettings) {
   absl::Notification login_notification;
   account_manager().SetAccount(account);
   service_->GetAccountManager()->Login(
+      "test_client_id", "test_client_secret",
       [&](AccountManager::Account account) {
         EXPECT_EQ(account.id, kTestAccountId);
         login_notification.Notify();
@@ -4536,6 +4539,7 @@ TEST_F(NearbySharingServiceImplTest, LogoutShouldSetValidVisibility) {
   absl::Notification login_notification;
   account_manager().SetAccount(account);
   service_->GetAccountManager()->Login(
+      "test_client_id", "test_client_secret",
       [&](AccountManager::Account account) {
         EXPECT_EQ(account.id, kTestAccountId);
         login_notification.Notify();
@@ -4563,6 +4567,7 @@ TEST_F(NearbySharingServiceImplTest, LogoutShouldSetValidVisibility) {
   absl::Notification login2_notification;
   account_manager().SetAccount(account);
   service_->GetAccountManager()->Login(
+      "test_client_id", "test_client_secret",
       [&](AccountManager::Account account) {
         EXPECT_EQ(account.id, kTestAccountId);
         login2_notification.Notify();
@@ -4605,6 +4610,7 @@ TEST_F(NearbySharingServiceImplTest, LoginAndLogoutNoStopRunningSurfaces) {
   account.id = kTestAccountId;
   account_manager().SetAccount(account);
   service_->GetAccountManager()->Login(
+      "test_client_id", "test_client_secret",
       [&](AccountManager::Account account) {
         EXPECT_EQ(account.id, kTestAccountId);
         notification.Notify();