diff --git a/core/java/android/view/WindowManagerPolicy.java b/core/java/android/view/WindowManagerPolicy.java
index 858cf4b82c2d5..bd203c8737639 100644
--- a/core/java/android/view/WindowManagerPolicy.java
+++ b/core/java/android/view/WindowManagerPolicy.java
@@ -124,8 +124,6 @@ public interface WindowManagerPolicy {
      * to prepareAddWindow() until removeWindow().
      */
     public interface WindowState {
-        public final static int UNKNOWN_TASK_ID = -1;
-
         /**
          * Return the uid of the app that owns this window.
          */
@@ -274,7 +272,7 @@ public interface WindowManagerPolicy {
          * Get the layer at which this window's surface will be Z-ordered.
          */
         public int getSurfaceLayer();
-
+        
         /**
          * Return the token for the application (actually activity) that owns 
          * this window.  May return null for system windows. 
@@ -283,11 +281,6 @@ public interface WindowManagerPolicy {
          */
         public IApplicationToken getAppToken();
 
-        /**
-         * Return the taskId of the task that owns this window.
-         */
-        public int getTaskId();
-
         /**
          * Return true if, at any point, the application token associated with 
          * this window has actually displayed any windows.  This is most useful 
diff --git a/policy/src/com/android/internal/policy/impl/PhoneWindowManager.java b/policy/src/com/android/internal/policy/impl/PhoneWindowManager.java
index 41705efc5ffc6..3c23c6e56cd09 100644
--- a/policy/src/com/android/internal/policy/impl/PhoneWindowManager.java
+++ b/policy/src/com/android/internal/policy/impl/PhoneWindowManager.java
@@ -106,7 +106,6 @@ import java.io.File;
 import java.io.FileReader;
 import java.io.IOException;
 import java.io.PrintWriter;
-import java.util.HashSet;
 
 import static android.view.WindowManager.LayoutParams.*;
 import static android.view.WindowManagerPolicy.WindowManagerFuncs.LID_ABSENT;
@@ -375,7 +374,7 @@ public class PhoneWindowManager implements WindowManagerPolicy {
     static final Rect mTmpNavigationFrame = new Rect();
 
     WindowState mTopFullscreenOpaqueWindowState;
-    HashSet<Integer> mTasksToBeHidden = new HashSet<Integer>();
+    boolean mHideWindowBehindKeyguard;
     boolean mTopIsFullscreen;
     boolean mForceStatusBar;
     boolean mForceStatusBarFromKeyguard;
@@ -3367,7 +3366,7 @@ public class PhoneWindowManager implements WindowManagerPolicy {
     @Override
     public void beginPostLayoutPolicyLw(int displayWidth, int displayHeight) {
         mTopFullscreenOpaqueWindowState = null;
-        mTasksToBeHidden.clear();
+        mHideWindowBehindKeyguard = false;
         mForceStatusBar = false;
         mForceStatusBarFromKeyguard = false;
         mForcingShowNavBar = false;
@@ -3418,18 +3417,12 @@ public class PhoneWindowManager implements WindowManagerPolicy {
 
             final boolean showWhenLocked = (fl & FLAG_SHOW_WHEN_LOCKED) != 0;
             if (appWindow) {
-                final int taskId = win.getTaskId();
-                if (taskId != WindowState.UNKNOWN_TASK_ID && showWhenLocked) {
-                    mTasksToBeHidden.remove(taskId);
-                } else {
-                    mTasksToBeHidden.add(taskId);
-                }
                 if (attrs.x == 0 && attrs.y == 0
                         && attrs.width == WindowManager.LayoutParams.MATCH_PARENT
                         && attrs.height == WindowManager.LayoutParams.MATCH_PARENT) {
                     if (DEBUG_LAYOUT) Slog.v(TAG, "Fullscreen window: " + win);
                     mTopFullscreenOpaqueWindowState = win;
-                    if (mTasksToBeHidden.isEmpty()) {
+                    if (!mHideWindowBehindKeyguard) {
                         if (showWhenLocked) {
                             if (DEBUG_LAYOUT) Slog.v(TAG,
                                     "Setting mHideLockScreen to true by win " + win);
@@ -3449,6 +3442,8 @@ public class PhoneWindowManager implements WindowManagerPolicy {
                     if ((fl & FLAG_ALLOW_LOCK_WHILE_SCREEN_ON) != 0) {
                         mAllowLockscreenWhenOn = true;
                     }
+                } else if (!showWhenLocked) {
+                    mHideWindowBehindKeyguard = true;
                 }
             }
         }
diff --git a/services/core/java/com/android/server/wm/WindowState.java b/services/core/java/com/android/server/wm/WindowState.java
index 3434053daa9ca..2c0e99ed12899 100644
--- a/services/core/java/com/android/server/wm/WindowState.java
+++ b/services/core/java/com/android/server/wm/WindowState.java
@@ -709,11 +709,6 @@ final class WindowState implements WindowManagerPolicy.WindowState {
         return mAppToken != null ? mAppToken.appToken : null;
     }
 
-    @Override
-    public int getTaskId() {
-        return mAppToken != null ? mAppToken.groupId : UNKNOWN_TASK_ID;
-    }
-
     boolean setInsetsChanged() {
         mOverscanInsetsChanged |= !mLastOverscanInsets.equals(mOverscanInsets);
         mContentInsetsChanged |= !mLastContentInsets.equals(mContentInsets);