perf: register system callbacks on background thread

bugsnag-android-core/src/main/java/com/bugsnag/android/Client.java

@@ -74,11 +74,11 @@ public class Client implements MetadataAware, CallbackAware, UserAware {
 
     final SessionTracker sessionTracker;
 
-    private final SystemBroadcastReceiver systemBroadcastReceiver;
+    final SystemBroadcastReceiver systemBroadcastReceiver;
     private final ActivityBreadcrumbCollector activityBreadcrumbCollector;
     private final SessionLifecycleCallback sessionLifecycleCallback;
 
-    private final Connectivity connectivity;
+    final Connectivity connectivity;
 
     @Nullable
     private final StorageManager storageManager;
@@ -223,11 +223,9 @@ public Unit invoke(String activity, Map<String, ?> metadata) {
             exceptionHandler.install();
         }
 
-        // register a receiver for automatic breadcrumbs
-        systemBroadcastReceiver = SystemBroadcastReceiver.register(this, logger, bgTaskService);
-
-        registerOrientationChangeListener();
-        registerMemoryTrimListener();
+        // register listeners for system events in the background.
+        systemBroadcastReceiver = new SystemBroadcastReceiver(this, logger);
+        registerListenersInBackground();
 
         // load last run info
         lastRunInfoStore = new LastRunInfoStore(immutableConfig);
@@ -236,8 +234,6 @@ public Unit invoke(String activity, Map<String, ?> metadata) {
         // initialise plugins before attempting to flush any errors
         loadPlugins(configuration);
 
-        connectivity.registerForNetworkChanges();
-
         // Flush any on-disk errors and sessions
         eventStore.flushOnLaunch();
         eventStore.flushAsync();
@@ -301,6 +297,27 @@ public Unit invoke(String activity, Map<String, ?> metadata) {
         this.exceptionHandler = exceptionHandler;
     }
 
+    /**
+     * Registers listeners for system events in the background. This offloads work from the main
+     * thread that collects useful information from callbacks, but that don't need to be done
+     * immediately on client construction.
+     */
+    void registerListenersInBackground() {
+        try {
+            bgTaskService.submitTask(TaskType.DEFAULT, new Runnable() {
+                @Override
+                public void run() {
+                    connectivity.registerForNetworkChanges();
+                    SystemBroadcastReceiver.register(appContext, systemBroadcastReceiver, logger);
+                    registerOrientationChangeListener();
+                    registerMemoryTrimListener();
+                }
+            });
+        } catch (RejectedExecutionException ex) {
+            logger.w("Failed to register for system events", ex);
+        }
+    }
+
     private LastRunInfo loadLastRunInfo() {
         LastRunInfo lastRunInfo = lastRunInfoStore.load();
         LastRunInfo currentRunInfo = new LastRunInfo(0, false, false);
@@ -342,7 +359,7 @@ private MetadataState copyMetadataState(@NonNull Configuration configuration) {
         return configuration.impl.metadataState.copy(copy);
     }
 
-    private void registerOrientationChangeListener() {
+    void registerOrientationChangeListener() {
         IntentFilter configFilter = new IntentFilter();
         configFilter.addAction(Intent.ACTION_CONFIGURATION_CHANGED);
         ConfigChangeReceiver receiver = new ConfigChangeReceiver(deviceDataCollector,
@@ -361,7 +378,7 @@ public Unit invoke(String oldOrientation, String newOrientation) {
         ContextExtensionsKt.registerReceiverSafe(appContext, receiver, configFilter, logger);
     }
 
-    private void registerMemoryTrimListener() {
+    void registerMemoryTrimListener() {
         appContext.registerComponentCallbacks(new ClientComponentCallbacks(
                 new Function1<Boolean, Unit>() {
                     @Override