PRImpl#getClient adds null check

Change:
* PaymentRequestImpl#getClient adds null check for
ComponentPaymentRequest.

Bug: 1114133

Change-Id: Id994b6a4d20d24f54a088a6b08b46cca330f538d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2341219Reviewed-by: Sahel Sharify <sahel@chromium.org>
Commit-Queue: Liquan (Max) Gu <maxlg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#795989}

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

@@ -2432,7 +2432,8 @@ public class PaymentRequestImpl
 
     @Nullable
     private PaymentRequestClient getClient() {
-        return mComponentPaymentRequestImpl.getClient();
+        return mComponentPaymentRequestImpl == null ? null
+                                                    : mComponentPaymentRequestImpl.getClient();
     }
 
     // Pre-condition: the client is not null.