More correct startup and shutdown procedures.

During IpManager startup, anything sending messages to the state machine
must not begin doing so until after the state machine has been started.
Reorder the constructor accordingly.

During shutdown, AvoidBadWifiTracker needs to unregister the registered
BroadcastReceiver and might as well also unregister the ContentObserver.

Bug: 33388922
Change-Id: I58e07f7ccddaab160c153bcfb69fd45f50bb8710

services/core/java/com/android/server/ConnectivityService.java

@@ -864,6 +864,7 @@ public class ConnectivityService extends IConnectivityManager.Stub
 
         mAvoidBadWifiTracker = createAvoidBadWifiTracker(
                 mContext, mHandler, () -> rematchForAvoidBadWifiUpdate());
+        mAvoidBadWifiTracker.start();
     }
 
     private NetworkRequest createInternetRequestForTransport(

services/net/java/android/net/util/AvoidBadWifiTracker.java

@@ -57,7 +57,11 @@ public class AvoidBadWifiTracker {
     private final Context mContext;
     private final Handler mHandler;
     private final Runnable mReevaluateRunnable;
+    private final Uri mUri;
+    private final ContentResolver mResolver;
     private final SettingObserver mSettingObserver;
+    private final BroadcastReceiver mBroadcastReceiver;
+
     private volatile boolean mAvoidBadWifi = true;
 
     public AvoidBadWifiTracker(Context ctx, Handler handler) {
@@ -68,19 +72,36 @@ public class AvoidBadWifiTracker {
         mContext = ctx;
         mHandler = handler;
         mReevaluateRunnable = () -> { if (update() && cb != null) cb.run(); };
+        mUri = Settings.Global.getUriFor(NETWORK_AVOID_BAD_WIFI);
+        mResolver = mContext.getContentResolver();
         mSettingObserver = new SettingObserver();
-
-        final IntentFilter intentFilter = new IntentFilter();
-        intentFilter.addAction(Intent.ACTION_CONFIGURATION_CHANGED);
-        mContext.registerReceiverAsUser(new BroadcastReceiver() {
+        mBroadcastReceiver = new BroadcastReceiver() {
+            @Override
             public void onReceive(Context context, Intent intent) {
                 reevaluate();
             }
-        }, UserHandle.ALL, intentFilter, null, null);
+        };
 
         update();
     }
 
+    public void start() {
+        mResolver.registerContentObserver(mUri, false, mSettingObserver);
+
+        final IntentFilter intentFilter = new IntentFilter();
+        intentFilter.addAction(Intent.ACTION_CONFIGURATION_CHANGED);
+        mContext.registerReceiverAsUser(
+                mBroadcastReceiver, UserHandle.ALL, intentFilter, null, null);
+
+        reevaluate();
+    }
+
+    public void shutdown() {
+        mResolver.unregisterContentObserver(mSettingObserver);
+
+        mContext.unregisterReceiver(mBroadcastReceiver);
+    }
+
     public boolean currentValue() {
         return mAvoidBadWifi;
     }
@@ -100,8 +121,7 @@ public class AvoidBadWifiTracker {
     }
 
     public String getSettingsValue() {
-        final ContentResolver resolver = mContext.getContentResolver();
-        return Settings.Global.getString(resolver, NETWORK_AVOID_BAD_WIFI);
+        return Settings.Global.getString(mResolver, NETWORK_AVOID_BAD_WIFI);
     }
 
     @VisibleForTesting
@@ -117,12 +137,8 @@ public class AvoidBadWifiTracker {
     }
 
     private class SettingObserver extends ContentObserver {
-        private final Uri mUri = Settings.Global.getUriFor(NETWORK_AVOID_BAD_WIFI);
-
         public SettingObserver() {
             super(null);
-            final ContentResolver resolver = mContext.getContentResolver();
-            resolver.registerContentObserver(mUri, false, this);
         }
 
         @Override