diff --git a/packages/CarSystemUI/AndroidManifest.xml b/packages/CarSystemUI/AndroidManifest.xml
index 195d4fe..261b9f5 100644
--- a/packages/CarSystemUI/AndroidManifest.xml
+++ b/packages/CarSystemUI/AndroidManifest.xml
@@ -21,4 +21,8 @@
         coreApp="true">
     <!-- This permission is required to monitor car power state. -->
     <uses-permission android:name="android.car.permission.CAR_POWER" />
+    <!-- This permission is required to get the trusted device list of a user. -->
+    <uses-permission android:name="android.car.permission.CAR_ENROLL_TRUST"/>
+    <!-- This permission is required to get bluetooth broadcast. -->
+    <uses-permission android:name="android.permission.BLUETOOTH" />
 </manifest>
diff --git a/packages/CarSystemUI/res/drawable/unlock_dialog_background.xml b/packages/CarSystemUI/res/drawable/unlock_dialog_background.xml
new file mode 100644
index 0000000..bec6ba7
--- /dev/null
+++ b/packages/CarSystemUI/res/drawable/unlock_dialog_background.xml
@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License
+  -->
+<shape xmlns:android="http://schemas.android.com/apk/res/android">
+  <solid android:color="@color/unlock_dialog_background_color"/>
+  <padding
+      android:bottom="@*android:dimen/car_padding_2"
+      android:left="@*android:dimen/car_padding_2"
+      android:right="@*android:dimen/car_padding_2"
+      android:top="@*android:dimen/car_padding_2"/>
+  <corners
+      android:radius="@dimen/unlock_dialog_radius"/>
+</shape>
\ No newline at end of file
diff --git a/packages/CarSystemUI/res/layout/trust_agent_unlock_dialog.xml b/packages/CarSystemUI/res/layout/trust_agent_unlock_dialog.xml
new file mode 100644
index 0000000..2d9901c
--- /dev/null
+++ b/packages/CarSystemUI/res/layout/trust_agent_unlock_dialog.xml
@@ -0,0 +1,72 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License
+  -->
+
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/layout"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:gravity="center">
+
+    <LinearLayout
+        android:layout_width="@dimen/unlock_dialog_width"
+        android:layout_height="wrap_content"
+        android:gravity="center"
+        android:layout_gravity="center"
+        android:orientation="vertical"
+        android:background="@drawable/unlock_dialog_background"
+        android:padding="@*android:dimen/car_padding_2">
+        <FrameLayout
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content">
+            <ProgressBar
+                android:layout_gravity="center"
+                android:layout_width="@dimen/unlock_dialog_progress_bar_size"
+                android:layout_height="@dimen/unlock_dialog_progress_bar_size" />
+            <ImageView
+                android:id="@+id/avatar"
+                android:layout_gravity="center"
+                android:layout_width="@dimen/unlock_dialog_avatar_size"
+                android:layout_height="@dimen/unlock_dialog_avatar_size"
+                android:scaleType="fitCenter"/>
+        </FrameLayout>
+
+        <TextView
+            android:id="@+id/user_name"
+            android:layout_height="wrap_content"
+            android:layout_width="wrap_content"
+            android:text="@string/unlock_dialog_default_user_name"
+            android:textSize="@*android:dimen/car_body1_size"
+            android:textColor="@android:color/white"/>
+
+        <TextView
+            android:id="@+id/unlocking_text"
+            android:layout_height="wrap_content"
+            android:layout_width="wrap_content"
+            android:layout_marginTop="@*android:dimen/car_padding_1"
+            android:text="@string/unlock_dialog_message_default"
+            android:textSize="@*android:dimen/car_body4_size"
+            android:textColor="@color/unlock_dialog_message_text_default"/>
+
+        <Button
+            android:id="@+id/enter_pin_button"
+            android:layout_marginTop="@*android:dimen/car_padding_1"
+            android:layout_height="wrap_content"
+            android:layout_width="wrap_content"
+            android:text="@string/unlock_dialog_button_text_pin"
+            style="@style/UnlockDialogButton"/>
+    </LinearLayout>
+</FrameLayout>
\ No newline at end of file
diff --git a/packages/CarSystemUI/res/values/colors_car.xml b/packages/CarSystemUI/res/values/colors_car.xml
index 69ab3f3..0a3f7aa 100644
--- a/packages/CarSystemUI/res/values/colors_car.xml
+++ b/packages/CarSystemUI/res/values/colors_car.xml
@@ -26,4 +26,9 @@
     <color name="car_user_switcher_add_user_background_color">@*android:color/car_dark_blue_grey_600</color>
     <color name="car_user_switcher_add_user_add_sign_color">@*android:color/car_body1_light</color>
 
+    <!-- colors for unlock dialog -->
+    <color name="unlock_dialog_background_color">#ff282a2d</color>
+    <color name="unlock_dialog_message_text_default">@*android:color/car_grey_400</color>
+    <color name="unlock_dialog_enter_pin_text_color">#ff66b5ff</color>
+
 </resources>
diff --git a/packages/CarSystemUI/res/values/dimens_car.xml b/packages/CarSystemUI/res/values/dimens_car.xml
index 42a7649..9cb09c9 100644
--- a/packages/CarSystemUI/res/values/dimens_car.xml
+++ b/packages/CarSystemUI/res/values/dimens_car.xml
@@ -43,4 +43,10 @@
     <!-- This must be the negative of car_user_switcher_container_height for the animation. -->
     <dimen name="car_user_switcher_container_anim_height">-420dp</dimen>
 
+    <!-- dimensions for the unlock dialog -->
+    <dimen name="unlock_dialog_width">500dp</dimen>
+    <dimen name="unlock_dialog_radius">16dp</dimen>
+    <dimen name="unlock_dialog_avatar_size">100dp</dimen>
+    <dimen name="unlock_dialog_progress_bar_size">140dp</dimen>
+
 </resources>
diff --git a/packages/CarSystemUI/res/values/integers_car.xml b/packages/CarSystemUI/res/values/integers_car.xml
index be2cb0d8..862ba75 100644
--- a/packages/CarSystemUI/res/values/integers_car.xml
+++ b/packages/CarSystemUI/res/values/integers_car.xml
@@ -31,5 +31,7 @@
     <!--Percentage of the screen height, from the bottom, that a notification panel being peeked
     at will result in remaining closed the panel if released-->
     <integer name="notification_settle_close_percentage">80</integer>
+    <!-- The delay before the unlock dialog pops up -->
+    <integer name="unlock_dialog_delay_ms">3000</integer>
 
 </resources>
diff --git a/packages/CarSystemUI/res/values/strings_car.xml b/packages/CarSystemUI/res/values/strings_car.xml
index 83e91c5..717692e 100644
--- a/packages/CarSystemUI/res/values/strings_car.xml
+++ b/packages/CarSystemUI/res/values/strings_car.xml
@@ -29,4 +29,19 @@
     <string name="user_add_user_message_setup">When you add a new user, that person needs to set up their space.</string>
     <!-- Message to inform user that the newly created user will have permissions to update apps for all other users. [CHAR LIMIT=100] -->
     <string name="user_add_user_message_update">Any user can update apps for all other users.</string>
+    <!-- Default messages displayed on the unlock dialog before unlock advertising started. [CHAR LIMIT=30]-->
+    <string name="unlock_dialog_message_default">Waiting\u2026</string>
+    <!-- Message to inform user that the IHU is looking for trusted device. [CHAR LIMIT=30] -->
+    <string name="unlock_dialog_message_start">Looking for trusted device\u2026</string>
+
+    <!-- Cancel Button text for user who has PIN as security lock. [CHAR LIMIT=30] -->
+    <string name="unlock_dialog_button_text_pin">Enter PIN instead</string>
+    <!-- Cancel Button text for user who has Pattern as security lock. [CHAR LIMIT=30] -->
+    <string name="unlock_dialog_button_text_pattern">Enter Pattern instead</string>
+    <!-- Cancel Button text for user who has Password as security lock. [CHAR LIMIT=30] -->
+    <string name="unlock_dialog_button_text_password">Enter Password instead</string>
+    <!-- Default user name shows on unlock dialog -->
+    <string name="unlock_dialog_default_user_name">Default Name</string>
+    <!-- Default title for unlock dialog -->
+    <string name="unlock_dialog_title">Unlock Dialogue</string>
 </resources>
diff --git a/packages/CarSystemUI/res/values/styles.xml b/packages/CarSystemUI/res/values/styles.xml
index 371bebd..a9423bf 100644
--- a/packages/CarSystemUI/res/values/styles.xml
+++ b/packages/CarSystemUI/res/values/styles.xml
@@ -46,4 +46,12 @@
         <item name="android:layout_width">96dp</item>
         <item name="android:background">@drawable/nav_button_background</item>
     </style>
+
+    <style name="UnlockDialogButton">
+        <item name="android:background">?android:attr/selectableItemBackground</item>
+        <item name="android:textAlignment">center</item>
+        <item name="android:textColor">@color/unlock_dialog_enter_pin_text_color</item>
+        <item name="android:paddingHorizontal">16dp</item>
+        <item name="android:textAllCaps">false</item>
+    </style>
 </resources>
\ No newline at end of file
diff --git a/packages/CarSystemUI/src/com/android/systemui/statusbar/car/CarStatusBar.java b/packages/CarSystemUI/src/com/android/systemui/statusbar/car/CarStatusBar.java
index da42d4f..aa5e852 100644
--- a/packages/CarSystemUI/src/com/android/systemui/statusbar/car/CarStatusBar.java
+++ b/packages/CarSystemUI/src/com/android/systemui/statusbar/car/CarStatusBar.java
@@ -26,6 +26,7 @@
 import android.car.drivingstate.CarDrivingStateEvent;
 import android.car.drivingstate.CarUxRestrictionsManager;
 import android.car.hardware.power.CarPowerManager.CarPowerStateListener;
+import android.car.trust.CarTrustAgentEnrollmentManager;
 import android.content.Context;
 import android.graphics.PixelFormat;
 import android.graphics.Rect;
@@ -1027,8 +1028,12 @@
         UserSwitcherController userSwitcherController =
                 Dependency.get(UserSwitcherController.class);
         if (userSwitcherController.useFullscreenUserSwitcher()) {
+            Car car = Car.createCar(mContext);
+            CarTrustAgentEnrollmentManager enrollmentManager = (CarTrustAgentEnrollmentManager) car
+                    .getCarManager(Car.CAR_TRUST_AGENT_ENROLLMENT_SERVICE);
             mFullscreenUserSwitcher = new FullscreenUserSwitcher(this,
-                    mStatusBarWindow.findViewById(R.id.fullscreen_user_switcher_stub), mContext);
+                    mStatusBarWindow.findViewById(R.id.fullscreen_user_switcher_stub),
+                    enrollmentManager, mContext);
         } else {
             super.createUserSwitcher();
         }
diff --git a/packages/CarSystemUI/src/com/android/systemui/statusbar/car/CarTrustAgentUnlockDialogHelper.java b/packages/CarSystemUI/src/com/android/systemui/statusbar/car/CarTrustAgentUnlockDialogHelper.java
new file mode 100644
index 0000000..78bb1bc
--- /dev/null
+++ b/packages/CarSystemUI/src/com/android/systemui/statusbar/car/CarTrustAgentUnlockDialogHelper.java
@@ -0,0 +1,240 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.systemui.statusbar.car;
+
+import android.app.admin.DevicePolicyManager;
+import android.bluetooth.BluetoothAdapter;
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+import android.graphics.PixelFormat;
+import android.os.Handler;
+import android.os.UserHandle;
+import android.os.UserManager;
+import android.util.Log;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.WindowManager;
+import android.widget.Button;
+import android.widget.ImageView;
+import android.widget.TextView;
+
+import com.android.internal.widget.LockPatternUtils;
+import com.android.systemui.R;
+
+/**
+ * A helper class displays an unlock dialog and receives broadcast about detecting trusted device
+ * & unlocking state to show the appropriate message on the dialog.
+ */
+class CarTrustAgentUnlockDialogHelper extends BroadcastReceiver{
+    private static final String TAG = CarTrustAgentUnlockDialogHelper.class.getSimpleName();
+
+    private final Context mContext;
+    private final WindowManager mWindowManager;
+    private final UserManager mUserManager;
+    private final WindowManager.LayoutParams mParams;
+    /**
+     * Not using Dialog because context passed from {@link FullscreenUserSwitcher} is not an
+     * activity.
+     */
+    private final View mUnlockDialog;
+    private final TextView mUnlockingText;
+    private final Button mButton;
+    private final IntentFilter mFilter;
+    private int mUid;
+    private boolean mIsDialogShowing;
+    private OnHideListener mOnHideListener;
+
+    CarTrustAgentUnlockDialogHelper(Context context) {
+        mContext = context;
+        mUserManager = mContext.getSystemService(UserManager.class);
+        mWindowManager = mContext.getSystemService(WindowManager.class);
+        mParams = createLayoutParams();
+        mFilter = getIntentFilter();
+
+        mParams.packageName = mContext.getPackageName();
+        mParams.setTitle(mContext.getString(R.string.unlock_dialog_title));
+
+        mUnlockDialog = LayoutInflater.from(mContext).inflate(
+            R.layout.trust_agent_unlock_dialog, null);
+        mUnlockDialog.setLayoutParams(mParams);
+
+        mUnlockingText = mUnlockDialog.findViewById(R.id.unlocking_text);
+        mButton = mUnlockDialog.findViewById(R.id.enter_pin_button);
+        mButton.setOnClickListener(v -> {
+            hideUnlockDialog(/* notifyOnHideListener= */true);
+            // TODO(b/138250105) Stop unlock advertising
+        });
+
+        BluetoothAdapter bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
+        if (bluetoothAdapter != null
+                && bluetoothAdapter.getLeState() == BluetoothAdapter.STATE_BLE_ON) {
+            mUnlockingText.setText(R.string.unlock_dialog_message_start);
+        }
+    }
+
+    /**
+     * This filter is listening on:
+     * {@link BluetoothAdapter#ACTION_BLE_STATE_CHANGED} for starting unlock advertising;
+     * {@link Intent#ACTION_USER_UNLOCKED} for IHU unlocked
+     */
+    private IntentFilter getIntentFilter() {
+        IntentFilter filter = new IntentFilter();
+        filter.addAction(BluetoothAdapter.ACTION_BLE_STATE_CHANGED);
+        filter.addAction(Intent.ACTION_USER_UNLOCKED);
+        return filter;
+    }
+
+    /**
+     * Show dialog for the given user
+     */
+    void showUnlockDialog(int uid, OnHideListener listener) {
+        showUnlockDialogAfterDelay(uid, 0, listener);
+    }
+
+    /**
+     * Show dialog for the given user after the certain time of delay has elapsed
+     *
+     * @param uid the user to unlock
+     * @param listener listener that listens to dialog hide
+     */
+    void showUnlockDialogAfterDelay(int uid, OnHideListener listener) {
+        long delayMillis = mContext.getResources().getInteger(R.integer.unlock_dialog_delay_ms);
+        showUnlockDialogAfterDelay(uid, delayMillis, listener);
+    }
+
+    /**
+     * Show dialog for the given user after the supplied delay has elapsed
+     */
+    private void showUnlockDialogAfterDelay(int uid, long delayMillis, OnHideListener listener) {
+        setUid(uid);
+        mOnHideListener = listener;
+        if (!mIsDialogShowing) {
+            logd("Receiver registered");
+            mContext.registerReceiverAsUser(this, UserHandle.ALL, mFilter,
+                    /* broadcastPermission= */ null,
+                    /* scheduler= */ null);
+            new Handler().postDelayed(() -> {
+                if (!mUserManager.isUserUnlocked(uid)) {
+                    logd("Showed unlock dialog for user: " + uid + " after " + delayMillis
+                            + " delay.");
+                    mWindowManager.addView(mUnlockDialog, mParams);
+                }
+            }, delayMillis);
+        }
+        mIsDialogShowing = true;
+    }
+
+    private void setUid(int uid) {
+        mUid = uid;
+        TextView userName = mUnlockDialog.findViewById(R.id.user_name);
+        userName.setText(mUserManager.getUserInfo(mUid).name);
+        ImageView avatar = mUnlockDialog.findViewById(R.id.avatar);
+        avatar.setImageBitmap(mUserManager.getUserIcon(mUid));
+        setButtonText();
+    }
+
+    private void hideUnlockDialog(boolean notifyOnHideListener) {
+        if (!mIsDialogShowing) {
+            return;
+        }
+        mWindowManager.removeView(mUnlockDialog);
+        logd("Receiver unregistered");
+        mContext.unregisterReceiver(this);
+        if (notifyOnHideListener && mOnHideListener != null) {
+            mOnHideListener.onHide();
+        }
+        mIsDialogShowing = false;
+    }
+
+    @Override
+    public void onReceive(Context context, Intent intent) {
+        String action = intent.getAction();
+        if (action == null) {
+            return;
+        }
+        switch (action) {
+            case BluetoothAdapter.ACTION_BLE_STATE_CHANGED:
+                logd("Received ACTION_BLE_STATE_CHANGED");
+                int state = intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, -1);
+                if (state == BluetoothAdapter.STATE_BLE_ON) {
+                    logd("Received BLE_ON");
+                    mUnlockingText.setText(R.string.unlock_dialog_message_start);
+                }
+                break;
+            case Intent.ACTION_USER_UNLOCKED:
+                int uid = intent.getIntExtra(Intent.EXTRA_USER_HANDLE, -1);
+                if (uid == mUid) {
+                    logd("IHU unlocked");
+                    hideUnlockDialog(/* notifyOnHideListener= */false);
+                } else {
+                    Log.e(TAG, "Received ACTION_USER_UNLOCKED for unexpected uid: " + uid);
+                }
+                break;
+            default:
+                Log.e(TAG, "Encountered unexpected action when attempting to set "
+                        + "unlock state message: " + action);
+        }
+    }
+
+    // Set button text based on security lock type
+    private void setButtonText() {
+        LockPatternUtils lockPatternUtils = new LockPatternUtils(mContext);
+        int passwordQuality = lockPatternUtils.getActivePasswordQuality(mUid);
+        switch (passwordQuality) {
+            // PIN
+            case DevicePolicyManager.PASSWORD_QUALITY_NUMERIC_COMPLEX:
+            // Pattern
+            case DevicePolicyManager.PASSWORD_QUALITY_SOMETHING:
+                mButton.setText(R.string.unlock_dialog_button_text_pattern);
+                break;
+            // Password
+            case DevicePolicyManager.PASSWORD_QUALITY_MANAGED:
+                mButton.setText(R.string.unlock_dialog_button_text_password);
+                break;
+            default:
+                Log.e(TAG, "Encountered unexpected security type when attempting to set "
+                        + "button text:" + passwordQuality);
+        }
+    }
+
+    private WindowManager.LayoutParams createLayoutParams() {
+        return new WindowManager.LayoutParams(
+                WindowManager.LayoutParams.MATCH_PARENT,
+                WindowManager.LayoutParams.MATCH_PARENT,
+                WindowManager.LayoutParams.TYPE_KEYGUARD_DIALOG,
+                WindowManager.LayoutParams.FLAG_FULLSCREEN
+                        | WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS
+                        | WindowManager.LayoutParams.FLAG_TRANSLUCENT_NAVIGATION,
+                PixelFormat.TRANSLUCENT
+        );
+    }
+
+    private void logd(String message) {
+        if (Log.isLoggable(TAG, Log.DEBUG)) {
+            Log.d(TAG, message);
+        }
+    }
+
+    /**
+     * Listener used to notify when the dialog is hidden
+     */
+    interface OnHideListener {
+        void onHide();
+    }
+}
diff --git a/packages/CarSystemUI/src/com/android/systemui/statusbar/car/FullscreenUserSwitcher.java b/packages/CarSystemUI/src/com/android/systemui/statusbar/car/FullscreenUserSwitcher.java
index 0a167d9..7cd6adb 100644
--- a/packages/CarSystemUI/src/com/android/systemui/statusbar/car/FullscreenUserSwitcher.java
+++ b/packages/CarSystemUI/src/com/android/systemui/statusbar/car/FullscreenUserSwitcher.java
@@ -18,29 +18,60 @@
 
 import android.animation.Animator;
 import android.animation.AnimatorListenerAdapter;
+import android.car.trust.CarTrustAgentEnrollmentManager;
+import android.car.userlib.CarUserManagerHelper;
+import android.content.BroadcastReceiver;
 import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+import android.content.pm.UserInfo;
+import android.os.UserHandle;
+import android.os.UserManager;
+import android.util.Log;
 import android.view.View;
 import android.view.ViewStub;
 
 import androidx.recyclerview.widget.GridLayoutManager;
 
 import com.android.systemui.R;
+import com.android.systemui.statusbar.car.UserGridRecyclerView.UserRecord;
 
 /**
  * Manages the fullscreen user switcher.
  */
 public class FullscreenUserSwitcher {
+    private static final String TAG = FullscreenUserSwitcher.class.getSimpleName();
+    // Because user 0 is headless, user count for single user is 2
+    private static final int NUMBER_OF_BACKGROUND_USERS = 1;
     private final UserGridRecyclerView mUserGridView;
     private final View mParent;
     private final int mShortAnimDuration;
     private final CarStatusBar mStatusBar;
+    private final Context mContext;
+    private final UserManager mUserManager;
+    private final CarTrustAgentEnrollmentManager mEnrollmentManager;
+    private CarTrustAgentUnlockDialogHelper mUnlockDialogHelper;
+    private UserGridRecyclerView.UserRecord mSelectedUser;
+    private CarUserManagerHelper mCarUserManagerHelper;
+    private final BroadcastReceiver mUserUnlockReceiver = new BroadcastReceiver() {
+        @Override
+        public void onReceive(Context context, Intent intent) {
+            if (Log.isLoggable(TAG, Log.DEBUG)) {
+                Log.d(TAG, "user 0 is unlocked, SharedPreference is accessible.");
+            }
+            showDialogForInitialUser();
+            mContext.unregisterReceiver(mUserUnlockReceiver);
+        }
+    };
 
-    public FullscreenUserSwitcher(CarStatusBar statusBar, ViewStub containerStub, Context context) {
+
+    public FullscreenUserSwitcher(CarStatusBar statusBar, ViewStub containerStub,
+            CarTrustAgentEnrollmentManager enrollmentManager, Context context) {
         mStatusBar = statusBar;
         mParent = containerStub.inflate();
-        // Hide the user grid by default. It will only be made visible by clicking on a cancel
-        // button in a bouncer.
-        hide();
+        mEnrollmentManager = enrollmentManager;
+        mContext = context;
+
         View container = mParent.findViewById(R.id.container);
 
         // Initialize user grid.
@@ -50,9 +81,51 @@
         mUserGridView.setLayoutManager(layoutManager);
         mUserGridView.buildAdapter();
         mUserGridView.setUserSelectionListener(this::onUserSelected);
+        mCarUserManagerHelper = new CarUserManagerHelper(context);
+        mUnlockDialogHelper = new CarTrustAgentUnlockDialogHelper(mContext);
+        mUserManager = mContext.getSystemService(UserManager.class);
 
         mShortAnimDuration = container.getResources()
                 .getInteger(android.R.integer.config_shortAnimTime);
+        IntentFilter filter = new IntentFilter(Intent.ACTION_USER_UNLOCKED);
+        if (mUserManager.isUserUnlocked(UserHandle.USER_SYSTEM)) {
+            // User0 is unlocked, switched to the initial user
+            showDialogForInitialUser();
+        } else {
+            // listen to USER_UNLOCKED
+            mContext.registerReceiverAsUser(mUserUnlockReceiver,
+                    UserHandle.getUserHandleForUid(UserHandle.USER_SYSTEM),
+                    filter,
+                    /* broadcastPermission= */ null,
+                    /* scheduler */ null);
+        }
+    }
+
+    private void showDialogForInitialUser() {
+        int initialUser = mCarUserManagerHelper.getInitialUser();
+        UserInfo initialUserInfo = mUserManager.getUserInfo(initialUser);
+        mSelectedUser = new UserRecord(initialUserInfo,
+                /* isStartGuestSession= */ false,
+                /* isAddUser= */ false,
+                /* isForeground= */ true);
+        // For single user without trusted device, hide the user switcher.
+        if (!hasMultipleUsers() && !hasTrustedDevice(initialUser)) {
+            dismissUserSwitcher();
+            return;
+        }
+        // Show unlock dialog for initial user
+        if (hasTrustedDevice(initialUser)) {
+            mUnlockDialogHelper.showUnlockDialogAfterDelay(initialUser,
+                    () -> dismissUserSwitcher());
+        }
+    }
+
+    /**
+     * Check if there is only one possible user to login in.
+     * In a Multi-User system there is always one background user (user 0)
+     */
+    private boolean hasMultipleUsers() {
+        return mUserManager.getUserCount() > NUMBER_OF_BACKGROUND_USERS + 1;
     }
 
     /**
@@ -77,14 +150,33 @@
     }
 
     /**
-     * Every time user clicks on an item in the switcher, we hide the switcher, either
-     * gradually or immediately.
+     * Every time user clicks on an item in the switcher, if the clicked user has no trusted device,
+     * we hide the switcher, either gradually or immediately.
      *
-     * We dismiss the entire keyguard if user clicked on the foreground user (user we're already
-     * logged in as).
+     * If the user has trusted device, we show an unlock dialog to notify user the unlock state.
+     * When the unlock dialog is dismissed by user, we hide the unlock dialog and the switcher.
+     *
+     * We dismiss the entire keyguard when we hide the switcher if user clicked on the foreground
+     * user (user we're already logged in as).
      */
     private void onUserSelected(UserGridRecyclerView.UserRecord record) {
-        if (record.mIsForeground) {
+        mSelectedUser = record;
+        if (hasTrustedDevice(record.mInfo.id)) {
+            mUnlockDialogHelper.showUnlockDialog(record.mInfo.id, () -> dismissUserSwitcher());
+            return;
+        }
+        if (Log.isLoggable(TAG, Log.DEBUG)) {
+            Log.d(TAG, "no trusted device enrolled for uid: " + record.mInfo.id);
+        }
+        dismissUserSwitcher();
+    }
+
+    private void dismissUserSwitcher() {
+        if (mSelectedUser == null) {
+            Log.e(TAG, "Request to dismiss user switcher, but no user selected");
+            return;
+        }
+        if (mSelectedUser.mIsForeground) {
             hide();
             mStatusBar.dismissKeyguard();
             return;
@@ -106,4 +198,8 @@
                 });
 
     }
+
+    private boolean hasTrustedDevice(int uid) {
+        return !mEnrollmentManager.getEnrolledDeviceInfoForUser(uid).isEmpty();
+    }
 }