Gracefully handle payment app crash.

chrome/android/java/src/org/chromium/chrome/browser/payments/AndroidPaymentApp.java

Index: chrome/android/java/src/org/chromium/chrome/browser/payments/AndroidPaymentApp.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/payments/AndroidPaymentApp.java b/chrome/android/java/src/org/chromium/chrome/browser/payments/AndroidPaymentApp.java
index f693c299c746d014ebe7c34d44103c2da2d4ff0a..922ca4aaa9c8c00a80714c4e7948b3037b2c7d55 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/payments/AndroidPaymentApp.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/payments/AndroidPaymentApp.java
@@ -169,6 +169,7 @@ public class AndroidPaymentApp extends PaymentInstrument implements PaymentApp,
             @Override
             public void run() {
                 ThreadUtils.assertOnUiThread();
+                if (mInstrumentsCallback == null) return;
                 List<PaymentInstrument> instruments = null;
                 if (instrument != null) {
                     instruments = new ArrayList<>();