Handle deprecated connectivity intent filter.

app/src/main/java/org/thoughtcrime/securesms/util/InternetConnectionObserver.kt

@@ -5,12 +5,52 @@ import android.content.Context
 import android.content.Intent
 import android.content.IntentFilter
 import android.net.ConnectivityManager
+import android.net.Network
+import android.os.Build
+import androidx.annotation.RequiresApi
 import io.reactivex.rxjava3.core.Observable
 import org.thoughtcrime.securesms.dependencies.ApplicationDependencies
 import org.thoughtcrime.securesms.jobmanager.impl.NetworkConstraint
 
 object InternetConnectionObserver {
-  fun observe(): Observable<Boolean> = Observable.create {
+  /**
+   * Observe network availability changes.
+   */
+  fun observe(): Observable<Boolean> {
+    return if (Build.VERSION.SDK_INT >= 24) {
+      observeApi24()
+    } else {
+      observeApi19()
+    }
+  }
+
+  @RequiresApi(24)
+  private fun observeApi24(): Observable<Boolean> {
+    return Observable.create {
+      val application = ApplicationDependencies.getApplication()
+      val connectivityManager = ServiceUtil.getConnectivityManager(application)
+
+      val callback = object : ConnectivityManager.NetworkCallback() {
+        override fun onAvailable(network: Network) {
+          it.onNext(true)
+        }
+
+        override fun onLost(network: Network) {
+          it.onNext(false)
+        }
+      }
+
+      connectivityManager.registerDefaultNetworkCallback(callback)
+
+      it.setCancellable {
+        connectivityManager.unregisterNetworkCallback(callback)
+      }
+    }
+  }
+
+  @Suppress("DEPRECATION")
+  private fun observeApi19(): Observable<Boolean> {
+    return Observable.create {
       val application = ApplicationDependencies.getApplication()
 
       val observer = object : BroadcastReceiver() {
@@ -25,3 +65,4 @@ object InternetConnectionObserver {
       application.registerReceiver(observer, IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION))
     }
   }
+}