[Payments] Don't show select when clicking in billing address drop.

chrome/android/java/src/org/chromium/chrome/browser/payments/ui/HintArrayAdapter.java

Index: chrome/android/java/src/org/chromium/chrome/browser/payments/ui/HintArrayAdapter.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/payments/ui/HintArrayAdapter.java b/chrome/android/java/src/org/chromium/chrome/browser/payments/ui/HintArrayAdapter.java
new file mode 100644
index 0000000000000000000000000000000000000000..02fcfc06ee82e86174ae621b964ff25b229a0e66
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/payments/ui/HintArrayAdapter.java
@@ -0,0 +1,39 @@
+// 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.ui;
+
+import android.content.Context;
+import android.widget.ArrayAdapter;
+
+import java.util.List;
+
+/**
+ * Subclass of ArrayAdapter used to display a dropdown hint that won't appear in the dropdown
+ * options. The last element is the hint.
+ *
+ * @param <T> The type of element to be inserted into the adapter.
+ */
+public class HintArrayAdapter<T> extends ArrayAdapter<T> {
+
+    /**
+     * Creates an array adapter for which the last element is not shown.
+     *
+     * @param context  The current context.
+     * @param resource The resource ID for a layout file containing a layout to use when
+     *                 instantiating views.
+     * @param objects  The objects to represent in the ListView, the last of which is not displayed
+     *                 in the dropdown, but is used as the hint.
+     */
+    public HintArrayAdapter(Context context, int resource, List<T> objects) {
+        super(context, resource, objects);
+    }
+
+    @Override
+    public int getCount() {
+        // Don't display last item, it is used as hint.
+        int count = super.getCount();
+        return count > 0 ? count - 1 : count;
+    }
+}