Workaround View.post issues to fix runtime crash

Using View.post was really dangerous because when the view wasn't
attached, it got posted on the run queue of the *calling* thread.
However, that run queue was never executed until power down, and
then it was executed from the PowerManagerService thread, because
that was the calling thread when we posted it. Work around this by
using a solid Handler.

Bug: 22820787
Change-Id: Id60e49e859558993256fae0403236f2e4b6f1075

services/core/java/com/android/server/policy/keyguard/KeyguardServiceDelegate.java

@@ -8,6 +8,7 @@ import android.content.pm.ActivityInfo;
 import android.content.res.Resources;
 import android.graphics.PixelFormat;
 import android.os.Bundle;
+import android.os.Handler;
 import android.os.IBinder;
 import android.os.RemoteException;
 import android.os.UserHandle;
@@ -34,6 +35,7 @@ public class KeyguardServiceDelegate {
     protected KeyguardServiceWrapper mKeyguardService;
     private final Context mContext;
     private final View mScrim; // shown if keyguard crashes
+    private final Handler mScrimHandler;
     private final KeyguardState mKeyguardState = new KeyguardState();
     private DrawnListener mDrawnListenerWhenConnect;
 
@@ -103,6 +105,7 @@ public class KeyguardServiceDelegate {
     public KeyguardServiceDelegate(Context context) {
         mContext = context;
         mScrim = createScrim(context);
+        mScrimHandler = new Handler();
     }
 
     public void bindService(Context context) {
@@ -337,7 +340,7 @@ public class KeyguardServiceDelegate {
     public void showScrim() {
         synchronized (mKeyguardState) {
             if (!mKeyguardState.deviceHasKeyguard) return;
-            mScrim.post(new Runnable() {
+            mScrimHandler.post(new Runnable() {
                 @Override
                 public void run() {
                     mScrim.setVisibility(View.VISIBLE);
@@ -347,7 +350,7 @@ public class KeyguardServiceDelegate {
     }
 
     public void hideScrim() {
-        mScrim.post(new Runnable() {
+        mScrimHandler.post(new Runnable() {
             @Override
             public void run() {
                 mScrim.setVisibility(View.GONE);