Support 3P oauth flow.

PiperOrigin-RevId: 663964316

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(

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_) {

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(

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));