Disabled flaky testCallCanMakePayment()

In PaymentRequestServiceWorkerPaymentAppTest.java.
It's flaky, see bug.

TBR=rouslan@chromium.org,mathp@chromium.org

No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 789532
Change-Id: I62d087abd95c37fd32fdef123c2d4bf847d2e4ac
Reviewed-on: https://chromium-review.googlesource.com/796417Reviewed-by: Henrik Boström <hbos@chromium.org>
Commit-Queue: Henrik Boström <hbos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#520097}

chrome/android/javatests/src/org/chromium/chrome/browser/payments/PaymentRequestServiceWorkerPaymentAppTest.java

@@ -328,6 +328,7 @@ public class PaymentRequestServiceWorkerPaymentAppTest {
     @Test
     @MediumTest
     @Feature({"Payments"})
+    @DisabledTest(message = "Flaky. See crbug.com/789532")
     public void testCallCanMakePayment()
             throws InterruptedException, ExecutionException, TimeoutException {
         String[] supportedMethodNames = {"https://bobpay.com", "basic-card"};