[Payments] Add ability to show additional text for OptionSections

* Add ability to display additional text above the PaymentOption
  lists.

* Shipping address section now has the option to display text
  saying that the user needs to select a shipping address to
  update the shipping options.

* Optional shipping address section text disappears once the
  user selects an option.

BUG=603635

Review-Url: https://codereview.chromium.org/2040623002
Cr-Commit-Position: refs/heads/master@{#397900}

chrome/android/java/res/values-v17/styles.xml

@@ -458,6 +458,8 @@
     <style name="PaymentsUiSectionDescriptiveText">
         <item name="android:textColor">@color/descriptive_text_color</item>
         <item name="android:textSize">14sp</item>
+    </style>
+    <style name="PaymentsUiSectionDescriptiveTextEndAligned" parent="PaymentsUiSectionDescriptiveText">
         <item name="android:textAlignment">viewEnd</item>
     </style>
     <style name="PaymentsUiSectionAddButtonLabel">

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

@@ -583,6 +583,11 @@ public class PaymentRequestImpl implements PaymentRequest, PaymentRequestUI.Clie
         closeUI(false);
     }
 
+    @Override
+    public boolean merchantNeedsShippingAddress() {
+        return mMerchantNeedsShippingAddress;
+    }
+
     /**
      * Called by the merchant website to abort the payment.
      */

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

@@ -57,7 +57,7 @@ import java.util.List;
  * The PaymentRequest UI.
  */
 public class PaymentRequestUI implements DialogInterface.OnDismissListener, View.OnClickListener,
-        PaymentRequestSection.PaymentsSectionDelegate {
+        PaymentRequestSection.SectionDelegate {
     public static final int TYPE_SHIPPING_ADDRESSES = 1;
     public static final int TYPE_SHIPPING_OPTIONS = 2;
     public static final int TYPE_PAYMENT_METHODS = 3;
@@ -119,6 +119,12 @@ public class PaymentRequestUI implements DialogInterface.OnDismissListener, View
          * or the “X” button in UI.
          */
         void onDismiss();
+
+        /**
+         * Checks if the merchant needs a shipping address to provide the shipping options.
+         * @return Whether or not the merchant needs a shipping address.
+         */
+        boolean merchantNeedsShippingAddress();
     }
 
     /**
@@ -697,6 +703,18 @@ public class PaymentRequestUI implements DialogInterface.OnDismissListener, View
         if (!mIsClientClosing) mClient.onDismiss();
     }
 
+    @Override
+    public String getAdditionalText(OptionSection section) {
+        if (section == mShippingAddressSection) {
+            int selectedItemIndex = mShippingAddressSectionInformation.getSelectedItemIndex();
+            boolean isNecessary = mClient.merchantNeedsShippingAddress()
+                    && selectedItemIndex == SectionInformation.NO_SELECTION;
+            return isNecessary ? mContext.getString(
+                    R.string.payments_select_shipping_address_for_shipping_methods) : null;
+        }
+        return null;
+    }
+
     /**
      * Animates the whole dialog fading in and darkening everything else on screen.
      * This particular animation is not tracked because it is not meant to be cancelable.

chrome/android/java/strings/android_chrome_strings.grd

@@ -2432,6 +2432,9 @@ You can control the Physical Web in Chrome Settings.
       <message name="IDS_PAYMENTS_ADD_PAYMENT_INSTRUMENT" desc="Text on a button that lets a user add a new payment method, like a credit card.">
         Add card
       </message>
+      <message name="IDS_PAYMENTS_SELECT_SHIPPING_ADDRESS_FOR_SHIPPING_METHODS" desc="Text implying that a user needs to pick a shipping address to see the shipping methods.">
+        Select a shipping address to check shipping methods.
+      </message>
 
       <!-- Migration strings -->
       <message name="IDS_TAB_SWITCHER_CALLOUT_HEADER" desc="Header for the Tab Switcher callout.">