Merge "Start keyguard docs" into sc-v2-dev

# Keyguard (aka Lockscreen)

Keyguard is responsible for:

1. Handling authentication to allow the user to unlock the device, via biometrics or [KeyguardBouncer][1]

2. Displaying informational content such as the time, notifications, and smartspace

3. Always-on Display (AOD)

Keyguard is the first screen available when turning on the device, as long as the user has not specified a security method of NONE.

[1]: /frameworks/base/packages/SystemUI/docs/keyguard/bouncer.md

# Bouncer

[KeyguardBouncer][1] is the component responsible for displaying the security method set by the user (password, PIN, pattern) as well as SIM-related security methods, allowing the user to unlock the device or SIM.

## Components

The bouncer contains a hierarchy of controllers/views to render the user's security method and to manage the authentication attempts.

1. [KeyguardBouncer][1] - Entrypoint for managing the bouncer visibility.

  1. [KeyguardHostViewController][2] - Intercepts media keys. Can most likely be merged with the next item.

    1. [KeyguardSecurityContainerController][3] - Manages unlock attempt responses, one-handed use

       1. [KeyguardSecurityViewFlipperController][4] - Based upon the [KeyguardSecurityModel#SecurityMode][5], will instantiate the required view and controller. PIN, Pattern, etc.

[1]: /frameworks/base/packages/SystemUI/com/android/systemui/statusbar/phone/KeyguardBouncer

[2]: /frameworks/base/packages/SystemUI/com/android/keyguard/KeyguardHostViewController

[3]: /frameworks/base/packages/SystemUI/com/android/keyguard/KeyguardSecurityContainerController

[4]: /frameworks/base/packages/SystemUI/com/android/keyguard/KeyguardSecurityViewFlipperController

[5]: /frameworks/base/packages/SystemUI/com/android/keyguard/KeyguardSecurityModel

            android:singleLine="true"

            android:ellipsize="marquee"

            android:focusable="true" />

        <FrameLayout android:id="@+id/keyboard_bouncer_container"

        <FrameLayout android:id="@+id/keyguard_bouncer_container"

                     android:layout_height="0dp"

                     android:layout_width="match_parent"

                     android:layout_weight="1" />

import android.os.Bundle;

import android.view.View;

import android.view.ViewGroup;

import android.view.ViewRootImpl;

import com.android.systemui.keyguard.KeyguardViewMediator;

    /**

     * Registers the StatusBar to which this Keyguard View is mounted.

     * @param statusBar

     * @param container

     * @param notificationPanelViewController

     * @param biometricUnlockController

     * @param notificationContainer

     * @param bypassController

     */

    void registerStatusBar(StatusBar statusBar,

            ViewGroup container,

            NotificationPanelViewController notificationPanelViewController,

            BiometricUnlockController biometricUnlockController,

            View notificationContainer,

import android.view.RemoteAnimationTarget;

import android.view.SyncRtSurfaceTransactionApplier;

import android.view.View;

import android.view.ViewGroup;

import android.view.WindowManager;

import android.view.WindowManagerPolicyConstants;

import android.view.animation.Animation;

     * Registers the StatusBar to which the Keyguard View is mounted.

     *

     * @param statusBar

     * @param container

     * @param panelView

     * @param biometricUnlockController

     * @param notificationContainer

     * @return the View Controller for the Keyguard View this class is mediating.

     */

    public KeyguardViewController registerStatusBar(StatusBar statusBar,

            ViewGroup container, NotificationPanelViewController panelView,

            NotificationPanelViewController panelView,

            BiometricUnlockController biometricUnlockController,

            View notificationContainer, KeyguardBypassController bypassController) {

        mKeyguardViewControllerLazy.get().registerStatusBar(statusBar, container, panelView,

        mKeyguardViewControllerLazy.get().registerStatusBar(statusBar, panelView,

                biometricUnlockController, notificationContainer, bypassController);

        return mKeyguardViewControllerLazy.get();

    }