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

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser.payments;
 
 import android.content.Context;
 import android.os.Handler;
 import android.view.View;
 import android.view.ViewGroup;
@@ skipping 130 matching lines @@
                 mWebContentsRef.set(mViewCoreRef.get().getWebContents());
                 PaymentRequestUI.setObserverForTest(PaymentRequestTestBase.this);
                 PaymentRequestImpl.setObserverForTest(PaymentRequestTestBase.this);
                 CardUnmaskPrompt.setObserverForTest(PaymentRequestTestBase.this);
             }
         });
         assertWaitForPageScaleFactorMatch(1);
         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 {
         int callCount = helper.getCallCount();
         DOMUtils.clickNode(this, mViewCoreRef.get(), nodeId);
         helper.waitForCallback(callCount);
     }
 
     /** Clicks on an element in the payments UI. */
     protected void clickAndWait(final int resourceId, CallbackHelper helper)
@@ skipping 573 matching lines @@
                 List<PaymentItem> cart, JSONObject details,
                 InstrumentDetailsCallback detailsCallback) {
             detailsCallback.onInstrumentDetailsReady(
                     mMethodName, "{\"transaction\": 1337}");
         }
 
         @Override
         public void dismissInstrument() {}
     }
 }