[Payments] Style the add address option in billing address selection.

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

Index: chrome/android/java/src/org/chromium/chrome/browser/payments/ui/BillingAddressAdapter.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/payments/ui/BillingAddressAdapter.java b/chrome/android/java/src/org/chromium/chrome/browser/payments/ui/BillingAddressAdapter.java
new file mode 100644
index 0000000000000000000000000000000000000000..f14b2b967dd19d3f9bdb02b10d2b8d57625b25af
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/payments/ui/BillingAddressAdapter.java
@@ -0,0 +1,97 @@
+// 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.content.res.Resources;
+import android.graphics.Typeface;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ArrayAdapter;
+import android.widget.TextView;
+
+import org.chromium.base.ApiCompatibilityUtils;
+import org.chromium.chrome.R;
+import org.chromium.chrome.browser.widget.TintedDrawable;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Subclass of ArrayAdapter used to display a dropdown hint that won't appear in the expanded
+ * dropdown options but will be used when no element is selected. The last shown element will have a
+ * "+" icon on its left and a blue tint to indicate the option to add an element.
+ *
+ * @param <T> The type of element to be inserted into the adapter.
+ *
+ *
+ * collapsed view:       --------          Expanded view:   ------------
+ * (no item selected)   | hint   |                         | option 1   |
+ *                       --------                          |------------|
+ *                                                         | option 2   |
+ * collapsed view:       ----------                        |------------|
+ * (with selected item) | option X |                       | + option N | -> stylized and "+" icon
+ *                       ----------                        .------------.
+ *                                                         . hint       . -> hidden
+ *                                                         ..............
+ */
+public class BillingAddressAdapter<T> extends ArrayAdapter<T> {
+
+    /**
+     * Creates an array adapter for which the last element is a hint that is not shown in the
+     * expanded view and where the last shown element has a "+" icon on its left and has a blue
+     * tint.
+     *
+     * @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 will have a "+"
+     *                 icon on its left and will have a blue tint.
+     * @param hint     The element to be used as a hint when no element is selected. It is not taken
+     *                 into account in the count function and thus will not be displayed when in the
+     *                 expanded dropdown view.
+     */
+    public BillingAddressAdapter(Context context, int resource, List<T> objects, T hint) {
+        // Make a copy of objects so the hint is not added to the original list.
+        super(context, resource, new ArrayList<T>(objects));
+        // The hint is added as the last element. It will not be shown when the dropdown is
+        // expanded and not be taken into account in the getCount function.
+        add(hint);
+    }
+
+    @Override
+    public int getCount() {
+        // Don't display last item, it is used as hint.
+        int count = super.getCount();
+        return count > 0 ? count - 1 : count;
+    }
+
+    @Override
+    public View getDropDownView(int position, View convertView, ViewGroup parent) {
+        View view = super.getDropDownView(position, convertView, parent);
+
+        // Add a "+" icon and a blue tint to the last element.
+        if (position == getCount() - 1) {
+            TextView tv = (TextView) view;
+            Resources resources = getContext().getResources();
+
+            // Create the "+" icon, put it left of the text and add appropriate padding.
+            tv.setCompoundDrawablesWithIntrinsicBounds(
+                    TintedDrawable.constructTintedDrawable(
+                        resources, R.drawable.plus, R.color.light_active_color),
+                    null, null, null);
+            tv.setCompoundDrawablePadding(
+                    resources.getDimensionPixelSize(R.dimen.payments_section_large_spacing));
+
+            // Set the correct appearance, face and style for the text.
+            ApiCompatibilityUtils.setTextAppearance(tv, R.style.PaymentsUiSectionAddButtonLabel);
+            tv.setTypeface(Typeface.create(
+                    resources.getString(R.string.roboto_medium_typeface),
+                    R.integer.roboto_medium_textstyle));
+        }
+
+        return view;
+    }
+}