Add callback for Connection/Disconnection to Metro

Reviewed By: bnham

Differential Revision: D6447126

fbshipit-source-id: d4c8a4dfb65c2a378f7fe696c8617ff5f3c6cb68

ReactAndroid/src/main/java/com/facebook/react/devsupport/DevServerHelper.java

@@ -25,6 +25,7 @@ import com.facebook.react.modules.systeminfo.AndroidInfoHelpers;
 import com.facebook.react.packagerconnection.FileIoHandler;
 import com.facebook.react.packagerconnection.JSPackagerClient;
 import com.facebook.react.packagerconnection.NotificationOnlyHandler;
+import com.facebook.react.packagerconnection.ReconnectingWebSocket.ConnectionCallback;
 import com.facebook.react.packagerconnection.RequestHandler;
 import com.facebook.react.packagerconnection.RequestOnlyHandler;
 import com.facebook.react.packagerconnection.Responder;
@@ -92,6 +93,8 @@ public class DevServerHelper {
   }
 
   public interface PackagerCommandListener {
+    void onPackagerConnected();
+    void onPackagerDisconnected();
     void onPackagerReloadCommand();
     void onPackagerDevMenuCommand();
     void onCaptureHeapCommand(final Responder responder);
@@ -163,10 +166,24 @@ public class DevServerHelper {
         });
         handlers.putAll(new FileIoHandler().handlers());
 
+        ConnectionCallback onPackagerConnectedCallback =
+          new ConnectionCallback() {
+              @Override
+              public void onConnected() {
+                commandListener.onPackagerConnected();
+              }
+
+              @Override
+              public void onDisconnected() {
+                commandListener.onPackagerDisconnected();
+              }
+            };
+
         mPackagerClient = new JSPackagerClient(
             clientId,
             mSettings.getPackagerConnectionSettings(),
-            handlers);
+            handlers,
+            onPackagerConnectedCallback);
         mPackagerClient.init();
 
         return null;

ReactAndroid/src/main/java/com/facebook/react/devsupport/DevSupportManagerImpl.java

@@ -723,6 +723,16 @@ public class DevSupportManagerImpl implements
     return mLastErrorStack;
   }
 
+  @Override
+  public void onPackagerConnected() {
+    // No-op
+  }
+
+  @Override
+  public void onPackagerDisconnected() {
+    // No-op
+  }
+
   @Override
   public void onPackagerReloadCommand() {
     // Disable debugger to resume the JsVM & avoid thread locks while reloading

ReactAndroid/src/main/java/com/facebook/react/packagerconnection/JSPackagerClient.java

@@ -9,6 +9,7 @@
 package com.facebook.react.packagerconnection;
 
 import java.util.Map;
+import javax.annotation.Nullable;
 
 import android.net.Uri;
 
@@ -63,6 +64,13 @@ final public class JSPackagerClient implements ReconnectingWebSocket.MessageCall
   private Map<String, RequestHandler> mRequestHandlers;
 
   public JSPackagerClient(String clientId, PackagerConnectionSettings settings, Map<String, RequestHandler> requestHandlers) {
+    this(clientId, settings, requestHandlers, null);
+  }
+
+  public JSPackagerClient(
+      String clientId, PackagerConnectionSettings settings,
+      Map<String, RequestHandler> requestHandlers,
+      @Nullable ReconnectingWebSocket.ConnectionCallback connectionCallback) {
     super();
 
     Uri.Builder builder = new Uri.Builder();
@@ -74,7 +82,7 @@ final public class JSPackagerClient implements ReconnectingWebSocket.MessageCall
       .appendQueryParameter("clientid", clientId);
     String url = builder.build().toString();
 
-    mWebSocket = new ReconnectingWebSocket(url, this, null);
+    mWebSocket = new ReconnectingWebSocket(url, this, connectionCallback);
     mRequestHandlers = requestHandlers;
   }