Framework customization series (VI) -- shield fallbackhome mobile phone from pop-up during startup and directly enter the launcher

1. shielding FallbackHome Start Popup

Problem scenario ：Android Remove lock screen in system customization KeyGuard After the service , When the system is powered on, enter Launcher Before , There will be a pop-up window when the mobile phone is starting , This part mainly involves Settings Medium FallbackHome, The solution is as follows ：

2. Extended boot animation

Code path ： framework/services/core/java/com/android/server/wm/WindowManagerService.java

// Comment out the code that turns off the startup animation 
 /* if (!mBootAnimationStopped) {
      Trace.asyncTraceBegin(TRACE_TAG_WINDOW_MANAGER, "Stop bootanim", 0);
      // stop boot animation
      // formerly we would just kill the process, but we now ask it to exit so it
      // can choose where to stop the animation.
      SystemProperties.set("service.bootanim.exit", "1");
      mBootAnimationStopped = true;
  }

  if (!mForceDisplayEnabled && !checkBootAnimationCompleteLocked()) {
      if (DEBUG_BOOT) Slog.i(TAG_WM, "performEnableScreen: Waiting for anim complete");
      return;
  }

  try {
      IBinder surfaceFlinger &