Fix flicker while booting

There was a short period of time where KeyguardScrim already went
away but status bar wasn't drawn yet, so we didn't consider it as
a wallpaper target so the wallpaper was invisible for a couple of
frames. Now only remove the scrim after the status bar has fully
drawn.

Change-Id: Ibf23b9e1277b6ce06e4ce70c9b7a5db9cbefce00
Fixes: 29643498

services/core/java/com/android/server/policy/PhoneWindowManager.java

@@ -6397,6 +6397,9 @@ public class PhoneWindowManager implements WindowManagerPolicy {
             }
 
             mWindowManagerDrawComplete = true;
+            if (mKeyguardDelegate != null) {
+                mKeyguardDelegate.onDrawCompleteLw();
+            }
         }
 
         finishScreenTurningOn();
@@ -6866,7 +6869,8 @@ public class PhoneWindowManager implements WindowManagerPolicy {
     /** {@inheritDoc} */
     @Override
     public void systemReady() {
-        mKeyguardDelegate = new KeyguardServiceDelegate(mContext);
+        mKeyguardDelegate = new KeyguardServiceDelegate(mContext,
+                mWindowManagerFuncs.getWindowManagerLock());
         mKeyguardDelegate.onSystemReady();
 
         readCameraLensCoverState();

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

@@ -19,6 +19,7 @@ import android.view.ViewGroup;
 import android.view.WindowManager;
 import android.view.WindowManagerPolicy.OnKeyguardExitResult;
 
+import com.android.internal.annotations.GuardedBy;
 import com.android.internal.policy.IKeyguardDrawnCallback;
 import com.android.internal.policy.IKeyguardExitCallback;
 import com.android.internal.policy.IKeyguardService;
@@ -43,6 +44,7 @@ public class KeyguardServiceDelegate {
     private static final int INTERACTIVE_STATE_AWAKE = 1;
     private static final int INTERACTIVE_STATE_GOING_TO_SLEEP = 2;
 
+    private final Object mWindowManagerLock;
     protected KeyguardServiceWrapper mKeyguardService;
     private final Context mContext;
     private final View mScrim; // shown if keyguard crashes
@@ -50,6 +52,9 @@ public class KeyguardServiceDelegate {
     private final KeyguardState mKeyguardState = new KeyguardState();
     private DrawnListener mDrawnListenerWhenConnect;
 
+    @GuardedBy("mWindowManagerLock")
+    private boolean mHideScrimPending;
+
     private static final class KeyguardState {
         KeyguardState() {
             // Assume keyguard is showing and secure until we know for sure. This is here in
@@ -92,10 +97,12 @@ public class KeyguardServiceDelegate {
         @Override
         public void onDrawn() throws RemoteException {
             if (DEBUG) Log.v(TAG, "**** SHOWN CALLED ****");
+            synchronized (mWindowManagerLock) {
+                mHideScrimPending = true;
+            }
             if (mDrawnListener != null) {
                 mDrawnListener.onDrawn();
             }
-            hideScrim();
         }
     };
 
@@ -116,7 +123,8 @@ public class KeyguardServiceDelegate {
         }
     };
 
-    public KeyguardServiceDelegate(Context context) {
+    public KeyguardServiceDelegate(Context context, Object windowManagerLock) {
+        mWindowManagerLock = windowManagerLock;
         mContext = context;
         mScrimHandler = UiThread.getHandler();
         mScrim = createScrim(context, mScrimHandler);
@@ -355,6 +363,16 @@ public class KeyguardServiceDelegate {
         }
     }
 
+    /**
+     * Called when all windows were fully drawn.
+     */
+    public void onDrawCompleteLw() {
+        if (mHideScrimPending) {
+            hideScrim();
+            mHideScrimPending = false;
+        }
+    }
+
     private static View createScrim(Context context, Handler handler) {
         final View view = new View(context);