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

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

Index: chrome/android/java/src/org/chromium/chrome/browser/payments/PaymentRequestMetrics.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/payments/PaymentRequestMetrics.java b/chrome/android/java/src/org/chromium/chrome/browser/payments/PaymentRequestMetrics.java
index 6aa7e3f88dd99a52ed7e60d6df12e26967ac814f..8a1ed847ca96eb5e736cb65dcc0849a6ad69d0cb 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/payments/PaymentRequestMetrics.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/payments/PaymentRequestMetrics.java
@@ -46,9 +46,39 @@ public final class PaymentRequestMetrics {
     @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;
+
+    // The method name associated with an Android Pay transaction.
+    private static String sAndroidPaymentMethodName = "https://android.com/pay";
+
     // There should be no instance of PaymentRequestMetrics created.
     private PaymentRequestMetrics() {}
 
+    /**
+     * Returns the method name corresponding to an Android Pay transaction in Payment Request.
+     *
+     * @return The method name corresponding to an Android Pay transaction.
+     */
+    public static String getAndroidPayMethodName() {
+        return sAndroidPaymentMethodName;
+    }
+
+    /**
+     * Sets the method name associated with an Android Pay transaction to the value used in tests.
+     */
+    @VisibleForTesting
+    public static void setAndroidPayMethodNameForTest() {
+        sAndroidPaymentMethodName = "https://bobpay.com";
+    }

[please use gerrit instead, 2016/08/05 22:08:26]

I'm not a fan of global modifiable state, if I can avoid it. Let's hardcode
"https://android.com/pay" for metrics and use it in your metrics tests as well.
Add an optional "methodName" parameter to installPaymentApp() function. So your
new tests can call something like:

installPaymentApp("https://android.com/pay", IMMEDIATE_RESPONSE,
HAVE_INSTRUMENT);

Then you can hard-code the comparison in PaymentRequestImpl:

} else if (methodName.equals("https://android.com/pay")) {
    ...
}

[sebsg, 2016/08/08 16:16:50]

Done.

+
     /*
      * Records the metric that keeps track of what user information are requested by merchants to
      * complete a payment request.
@@ -66,4 +96,16 @@ public final class PaymentRequestMetrics {
         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);
+    }
 }