cros: Fix inconsistent SessionController state for tests

- Do not set ACTIVE state in StartRestoreAfterCrashSession and
  StartStubLoginSession. SessionStarted() call will do that. Setting
  it explicitly breaks tests such as AccessibilityManagerTest that
  has "--login-manager" but goes through StartRestoreAfterCrashSession
  code to initialize;
- CrashRestoreComplexTest should use GetLRULoggedInUsers instead
  of GetLoggedInUsers since it tests the user session order;
- Fix UserManagerBase to cover tests that add a non-existent user;
  - Make sure |logged_in_user_| preserves the order since its index is
    used as fake session id ATM;
  - Fire UserAddedToSession for such users;

BUG=648964
TEST=Existing tests.

Review-Url: https://codereview.chromium.org/2577903002
Cr-Commit-Position: refs/heads/master@{#438944}

chrome/browser/chromeos/login/crash_restore_browsertest.cc

@@ -157,7 +157,7 @@ IN_PROC_BROWSER_TEST_F(CrashRestoreComplexTest, RestoreSessionForThreeUsers) {
   EXPECT_EQ(account_id3_, user->GetAccountId());
   EXPECT_EQ(CryptohomeClient::GetStubSanitizedUsername(cryptohome_id3_),
             user->username_hash());
-  const user_manager::UserList& users = user_manager->GetLoggedInUsers();
+  const user_manager::UserList& users = user_manager->GetLRULoggedInUsers();
   ASSERT_EQ(3UL, users.size());
 
   // User that becomes active moves to the beginning of the list.

chrome/browser/chromeos/login/session/chrome_session_manager.cc

@@ -90,9 +90,6 @@ void StartRestoreAfterCrashSession(Profile* user_profile,
                                    const std::string& login_user_id) {
   base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
 
-  session_manager::SessionManager::Get()->SetSessionState(
-      session_manager::SessionState::ACTIVE);
-
   // TODO(xiyuan): Identify tests that do not set this kLoginUser flag but
   // still rely on "stub user" session. Keeping existing behavior to avoid
   // breaking tests.
@@ -152,9 +149,6 @@ void StartRestoreAfterCrashSession(Profile* user_profile,
 // Starts a user session with stub user.
 void StartStubLoginSession(Profile* user_profile,
                            const std::string& login_user_id) {
-  session_manager::SessionManager::Get()->SetSessionState(
-      session_manager::SessionState::ACTIVE);
-
   // For dev machines and stub user emulate as if sync has been initialized.
   SigninManagerFactory::GetForProfile(user_profile)
       ->SetAuthenticatedAccountInfo(login_user_id, login_user_id);

components/user_manager/user_manager_base.cc

@@ -182,14 +182,18 @@ void UserManagerBase::UserLoggedIn(const AccountId& account_id,
   active_user_->set_is_active(true);
   active_user_->set_username_hash(username_hash);
 
-  // Place user who just signed in to the top of the logged in users.
-  logged_in_users_.insert(logged_in_users_.begin(), active_user_);
+  logged_in_users_.push_back(active_user_);
   SetLRUUser(active_user_);
 
   if (!primary_user_) {
     primary_user_ = active_user_;
     if (primary_user_->HasGaiaAccount())
       SendGaiaUserLoginMetrics(account_id);
+  } else if (primary_user_ != active_user_) {
+    // This is only needed for tests where a new user session is created
+    // for non-existent user.
+    SetIsCurrentUserNew(true);
+    NotifyUserAddedToSession(active_user_, true /* user switch pending */);
   }
 
   UMA_HISTOGRAM_ENUMERATION(