[Payments] Fix the Payment Request histogram check failure in tests.

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

Index: chrome/android/javatests/src/org/chromium/chrome/browser/payments/PaymentRequestTestBase.java
diff --git a/chrome/android/javatests/src/org/chromium/chrome/browser/payments/PaymentRequestTestBase.java b/chrome/android/javatests/src/org/chromium/chrome/browser/payments/PaymentRequestTestBase.java
index 6670a6749dc8f6f0192b3a2c11830e542f42f41f..d72236b8713cc60540e81fdefc8a52c95ad862b8 100644
--- a/chrome/android/javatests/src/org/chromium/chrome/browser/payments/PaymentRequestTestBase.java
+++ b/chrome/android/javatests/src/org/chromium/chrome/browser/payments/PaymentRequestTestBase.java
@@ -148,6 +148,14 @@ abstract class PaymentRequestTestBase extends ChromeActivityTestCaseBase<ChromeT
         clickNodeAndWait(nodeId, helper);
     }
 
+    /* Resets the mUI when doing a second payment request in the same test. */

[please use gerrit instead, 2016/10/26 22:01:14]

/** Clicks the HTML node to bring up the UI a second time. */

mUI is more of an implementation detail. Don't put that in comments.

[sebsg, 2016/10/26 23:42:04]

Done.

+    protected void reTriggerUIAndWait(
+            String nodeId, PaymentsCallbackHelper<PaymentRequestUI> helper)
+            throws InterruptedException, ExecutionException, TimeoutException {
+        clickNodeAndWait(nodeId, (CallbackHelper) helper);

[please use gerrit instead, 2016/10/26 22:01:14]

No need to cast PaymentsCallbackHelper to CallbackHelper here. I was doing that
in triggerUIAndWait() because there're several triggerUIAndWait() calls. Some
take PaymentsCallbackHelper and one takes CallbackHelper. I wanted to make sure
that I'm calling the right one. There's only one clickNodeAndWait(). It will be
called no matter what.

[sebsg, 2016/10/26 23:42:04]

Done.

+        mUI = helper.getTarget();
+    }
+
     /** Clicks on an HTML node. */
     protected void clickNodeAndWait(String nodeId, CallbackHelper helper)
             throws InterruptedException, ExecutionException, TimeoutException {