[Payments] Add Payment Request metrics for selected payment method.

chrome/android/java/src/org/chromium/chrome/browser/payments/PaymentRequestMetrics.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 org.chromium.base.VisibleForTesting;
 import org.chromium.base.metrics.RecordHistogram;
 
 /**
@@ skipping 28 matching lines @@
     public static final int ABORT_REASON_INSTRUMENT_DETAILS_ERROR = 5;
     @VisibleForTesting
     public static final int ABORT_REASON_NO_MATCHING_PAYMENT_METHOD = 6;
     @VisibleForTesting
     public static final int ABORT_REASON_NO_SUPPORTED_PAYMENT_METHOD = 7;
     @VisibleForTesting
     public static final int ABORT_REASON_OTHER = 8;
     @VisibleForTesting
     public static final int ABORT_REASON_MAX = 9;
 
+    // PaymentRequestPaymentMethods defined in tools/metrics/histograms/histograms.xml.
+    @VisibleForTesting
+    public static final int SELECTED_METHOD_CREDIT_CARD = 0;
+    @VisibleForTesting
+    public static final int SELECTED_METHOD_ANDROID_PAY = 1;
+    @VisibleForTesting
+    public static final int SELECTED_METHOD_OTHER_PAYMENT_APP = 2;
+    @VisibleForTesting
+    public static final int SELECTED_METHOD_MAX = 3;
+
     // There should be no instance of PaymentRequestMetrics created.
     private PaymentRequestMetrics() {}
 
     /*
      * Records the metric that keeps track of what user information are requested by merchants to
      * complete a payment request.
      *
      * @param requestEmail Whether the merchant requested an email address.
      * @param requestPhone Whether the merchant requested a phone number.
      * @param requestShipping Whether the merchant requested a shipping address.
      */
     public static void recordRequestedInformationHistogram(boolean requestEmail,
             boolean requestPhone, boolean requestShipping) {
         int requestInformation =
                 (requestEmail ? REQUESTED_INFORMATION_EMAIL : 0)
                 | (requestPhone ? REQUESTED_INFORMATION_PHONE : 0)
                 | (requestShipping ? REQUESTED_INFORMATION_SHIPPING : 0);
         RecordHistogram.recordEnumeratedHistogram("PaymentRequest.RequestedInformation",
                 requestInformation, REQUESTED_INFORMATION_MAX);
     }
+
+    /*
+     * Records the metric that keeps track of what payment method was used to complete a Payment
+     * Request transaction.
+     *
+     * @param paymentMethod The payment method that was used to complete the current transaction.
+     */
+    public static void recordSelectedPaymentMethodHistogram(int paymentMethod) {
+        assert paymentMethod < SELECTED_METHOD_MAX;
+        RecordHistogram.recordEnumeratedHistogram("PaymentRequest.SelectedPaymentMethod",
+                paymentMethod, SELECTED_METHOD_MAX);
+    }
 }