Randomize the Android downloaded bundle filename

Author: jamesreggio

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

@@ -101,7 +101,7 @@ public class DevSupportManagerImpl implements
 
   private static final int JAVA_ERROR_COOKIE = -1;
   private static final int JSEXCEPTION_ERROR_COOKIE = -1;
-  private static final String JS_BUNDLE_FILE_NAME = "ReactNativeDevBundle.js";
+  private static final String JS_BUNDLE_FILE_FORMAT = "ReactNativeDevBundle.%d.js";
   private static enum ErrorType {
     JS,
     NATIVE
@@ -229,11 +229,15 @@ public void onReceive(Context context, Intent intent) {
     };
 
     // We store JS bundle loaded from dev server in a single destination in app's data dir.
+    // (We randomize the name in the event that there are multiple JS bridges running.)
     // In case when someone schedule 2 subsequent reloads it may happen that JS thread will
     // start reading first reload output while the second reload starts writing to the same
     // file. As this should only be the case in dev mode we leave it as it is.
     // TODO(6418010): Fix readers-writers problem in debug reload from HTTP server
-    mJSBundleTempFile = new File(applicationContext.getFilesDir(), JS_BUNDLE_FILE_NAME);
+    mJSBundleTempFile = new File(
+      applicationContext.getFilesDir(),
+      String.format(JS_BUNDLE_FILE_FORMAT, (int)(Math.random() * 1000000))
+    );
 
     mDefaultNativeModuleCallExceptionHandler = new DefaultNativeModuleCallExceptionHandler();