接着这篇 android 开机广播是在哪里发出的
找到了开机广播发出的地方，就可以添加一个自定义的开机广播了。

自定义开机广播的目的，
一是去掉原生开机广播，防止所有的应用都接收原生开机广播启动，消耗太多系统内存；
二是开机广播较慢，在进入主页后大概 1 分钟后才收到。

AN 9.0 ，在 frameworks/base/services/core/java/com/android/server/am/UserController.java 中，
修改 finishUserUnlockedCompleted 函数，

private void finishUserUnlockedCompleted(UserState uss) {
        final int userId = uss.mHandle.getIdentifier();
        synchronized (mLock) {
            // Bail if we ended up with a stale user
            if (mStartedUsers.get(uss.mHandle.getIdentifier()) != uss) return;
        }
        UserInfo userInfo = getUserInfo(userId);
        if (userInfo == null) {
            return;
        }
        // Only keep marching forward if user is actually unlocked
        if (!StorageManager.isUserKeyUnlocked(userId)) return;

        // Remember that we logged in
        mInjector.getUserManager().onUserLoggedIn(userId);

        if (!userInfo.isInitialized()) {
            if (userId != UserHandle.USER_SYSTEM) {
                Slog.d(TAG, "Initializing user #" + userId);
                Intent intent = new Intent(Intent.ACTION_USER_INITIALIZE);
                intent.addFlags(Intent.FLAG_RECEIVER_FOREGROUND
                        | Intent.FLAG_RECEIVER_INCLUDE_BACKGROUND);
                mInjector.broadcastIntent(intent, null,
                        new IIntentReceiver.Stub() {
                            @Override
                            public void performReceive(Intent intent, int resultCode,
                                    String data, Bundle extras, boolean ordered,
                                    boolean sticky, int sendingUser) {
                                // Note: performReceive is called with mService lock held
                                mInjector.getUserManager().makeInitialized(userInfo.id);
                            }
                        }, 0, null, null, null, AppOpsManager.OP_NONE,
                        null, true, false, MY_PID, SYSTEM_UID, userId);
            }
        }

        Slog.i(TAG, "Sending BOOT_COMPLETE user #" + userId);
        // Do not report secondary users, runtime restarts or first boot/upgrade
        if (userId == UserHandle.USER_SYSTEM
                && !mInjector.isRuntimeRestarted() && !mInjector.isFirstBootOrUpgrade()) {
            int uptimeSeconds = (int) (SystemClock.elapsedRealtime() / 1000);
            MetricsLogger.histogram(mInjector.getContext(), "framework_boot_completed",
                    uptimeSeconds);
        }
        
		// modify begin 
		Intent myIntent = new Intent("android.intent.action.MY_BOOT_COMPLETED");
		myIntent.addFlags(Intent.FLAG_RECEIVER_FOREGROUND);
		myIntent.setPackage("com.test.mypackage");
		mInjector.getContext().sendBroadcast(myIntent);
		Slog.d(UserController.TAG, "send forground MY_BOOT_COMPLETED");
		// modify end
		
        final Intent bootIntent = new Intent(Intent.ACTION_BOOT_COMPLETED, null);
        bootIntent.putExtra(Intent.EXTRA_USER_HANDLE, userId);
        bootIntent.addFlags(Intent.FLAG_RECEIVER_NO_ABORT
                | Intent.FLAG_RECEIVER_INCLUDE_BACKGROUND);
        mInjector.broadcastIntent(bootIntent, null, new IIntentReceiver.Stub() {
                    @Override
                    public void performReceive(Intent intent, int resultCode, String data,
                            Bundle extras, boolean ordered, boolean sticky, int sendingUser)
                            throws RemoteException {
                        Slog.i(UserController.TAG, "Finished processing BOOT_COMPLETED for u" + userId);
                    }
                }, 0, null, null,
                new String[]{android.Manifest.permission.RECEIVE_BOOT_COMPLETED},
                AppOpsManager.OP_NONE, null, true, false, MY_PID, SYSTEM_UID, userId);
    }

具体的修改说明，

1. 声明为前台广播，比后台广播快
   myIntent.addFlags(Intent.FLAG_RECEIVER_FOREGROUND);
2. 指定的应用可以接收。如果需要作为全局广播则去掉
   myIntent.setPackage(“com.test.mypackage”);

指定的应用既接收开机广播，也接收自定义的开机广播；
经过测试，自定义的开机广播比原生开机广播早1分钟左右。