[Payments] Field trial and flag to abort payment request if no card.

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

Index: chrome/android/java/src/org/chromium/chrome/browser/payments/NoCardAbortFieldTrial.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/payments/NoCardAbortFieldTrial.java b/chrome/android/java/src/org/chromium/chrome/browser/payments/NoCardAbortFieldTrial.java
new file mode 100644
index 0000000000000000000000000000000000000000..57bff1c6aa4c8cf8d40219050e6d333f15807f75
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/payments/NoCardAbortFieldTrial.java
@@ -0,0 +1,101 @@
+// 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.text.TextUtils;
+
+import org.chromium.base.CommandLine;
+import org.chromium.chrome.browser.ChromeSwitches;
+import org.chromium.components.variations.VariationsAssociatedData;
+
+/**
+ * Provides Field Trial support for the Abort If No Card experiment within Chrome for Android.
+ */
+public class NoCardAbortFieldTrial {
+    private static final String FIELD_TRIAL_NAME = "NoCardAbort";
+    private static final String ENABLED_PARAM = "enabled";
+    private static final String ENABLED_VALUE = "true";
+
+    // Cached value to avoid repeated and redundant JNI operations.
+    private static Boolean sEnabled;
+
+    /**
+     * Don't instantiate.
+     */
+    private NoCardAbortFieldTrial() {}
+
+    /**
+     * Checks the current Variations parameters associated with the active group as well as the
+     * Chrome preference to determine if the service is enabled.
+     * @return Whether No Card Abort is enabled or not.
+     */
+    public static boolean isEnabled() {
+        if (sEnabled == null) {
+            sEnabled = detectEnabled();
+        }
+        return sEnabled.booleanValue();
+    }
+
+    private static boolean detectEnabled() {
+        // Allow this user-flippable flag to disable the feature.
+        if (CommandLine.getInstance().hasSwitch(ChromeSwitches.DISABLE_NO_CARD_ABORT)) {
+            return false;
+        }
+
+        // Allow this user-flippable flag to enable the feature.
+        if (CommandLine.getInstance().hasSwitch(ChromeSwitches.ENABLE_NO_CARD_ABORT)) {
+            return true;
+        }
+
+        // Allow enabling the feature remotely.
+        if (getBooleanParam(ENABLED_PARAM)) {
+            return true;
+        }
+
+        return false;
+    }
+
+    // --------------------------------------------------------------------------------------------
+    // Helpers.
+    // --------------------------------------------------------------------------------------------
+
+    /**
+     * Gets a boolean Finch parameter, assuming the <paramName>="true" format.  Also checks for a
+     * command-line switch with the same name, for easy local testing.
+     * @param paramName The name of the Finch parameter (or command-line switch) to get a value for.
+     * @return Whether the Finch param is defined with a value "true", if there's a command-line
+     *         flag present with any value.
+     */
+    private static boolean getBooleanParam(String paramName) {
+        if (CommandLine.getInstance().hasSwitch(paramName)) {
+            return true;
+        }
+        return TextUtils.equals(ENABLED_VALUE,
+                VariationsAssociatedData.getVariationParamValue(FIELD_TRIAL_NAME, paramName));
+    }
+
+    /**
+     * Returns an integer value for a Finch parameter, or the default value if no parameter exists
+     * in the current configuration.  Also checks for a command-line switch with the same name.
+     * @param paramName The name of the Finch parameter (or command-line switch) to get a value for.
+     * @param defaultValue The default value to return when there's no param or switch.
+     * @return An integer value -- either the param or the default.
+     */
+    private static int getIntParamValueOrDefault(String paramName, int defaultValue) {
+        String value = CommandLine.getInstance().getSwitchValue(paramName);
+        if (TextUtils.isEmpty(value)) {
+            value = VariationsAssociatedData.getVariationParamValue(FIELD_TRIAL_NAME, paramName);
+        }
+        if (!TextUtils.isEmpty(value)) {
+            try {
+                return Integer.parseInt(value);
+            } catch (NumberFormatException e) {
+                return defaultValue;
+            }
+        }
+
+        return defaultValue;
+    }
+}