Add a Learn More link to the Physical Web opt-in activity

chrome/android/java/src/org/chromium/chrome/browser/physicalweb/PhysicalWebOptInActivity.java

Index: chrome/android/java/src/org/chromium/chrome/browser/physicalweb/PhysicalWebOptInActivity.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/physicalweb/PhysicalWebOptInActivity.java b/chrome/android/java/src/org/chromium/chrome/browser/physicalweb/PhysicalWebOptInActivity.java
index 58e7c9643de2d9928bfe9f58941fb32000cfd4d7..6b84a518c067403dbc43932f5bb718117a9b0c4e 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/physicalweb/PhysicalWebOptInActivity.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/physicalweb/PhysicalWebOptInActivity.java
@@ -6,24 +6,41 @@ package org.chromium.chrome.browser.physicalweb;
 
 import android.content.Context;
 import android.content.Intent;
+import android.net.Uri;
 import android.os.Bundle;
 import android.support.v7.app.AppCompatActivity;
+import android.text.SpannableString;
+import android.text.TextPaint;
+import android.text.method.LinkMovementMethod;
+import android.text.style.ClickableSpan;
 import android.view.View;
 import android.widget.Button;
+import android.widget.TextView;
 
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.preferences.privacy.PrivacyPreferencesManager;
+import org.chromium.ui.text.SpanApplier;
+import org.chromium.ui.text.SpanApplier.SpanInfo;
 
 /**
  * This activity invites the user to opt-in to the Physical Web feature.
  */
 public class PhysicalWebOptInActivity extends AppCompatActivity {
+    private static final String EXTRA_CUSTOM_TABS_SESSION =
+            "android.support.customtabs.extra.SESSION";
+    private static final String PHYSICAL_WEB_LEARN_MORE_URL =
+            "https://support.google.com/chrome/answer/6239299/";
+
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.physical_web_optin);
         PhysicalWebUma.onOptInNotificationPressed(this);
 
+        TextView description = (TextView) findViewById(R.id.physical_web_optin_description);
+        description.setMovementMethod(LinkMovementMethod.getInstance());
+        description.setText(getDescriptionText());
+
         Button declineButton = (Button) findViewById(R.id.physical_web_decline);
         declineButton.setOnClickListener(new View.OnClickListener() {
             @Override
@@ -56,4 +73,28 @@ public class PhysicalWebOptInActivity extends AppCompatActivity {
                 ListUrlsActivity.OPTIN_REFERER);
         return intent;
     }
+
+    private SpannableString getDescriptionText() {
+        return SpanApplier.applySpans(
+                getString(R.string.physical_web_optin_description),
+                new SpanInfo("<learnmore>", "</learnmore>", new ClickableSpan() {
+                    @Override
+                    public void onClick(View v) {
+                        Intent intent = new Intent(Intent.ACTION_VIEW,
+                                Uri.parse(PHYSICAL_WEB_LEARN_MORE_URL));
+                        // Add the SESSION extra to indicate we want a Chrome custom tab. This
+                        // allows the help page to open in the same task as the opt-in activity so
+                        // they can share a back stack.
+                        String session = null;
+                        intent.putExtra(EXTRA_CUSTOM_TABS_SESSION, session);
+                        PhysicalWebOptInActivity.this.startActivity(intent);
+                    }
+
+                    @Override
+                    public void updateDrawState(TextPaint ds) {
+                        // Color links but do not underline them.
+                        ds.setColor(ds.linkColor);
+                    }
+                }));
+    }
 }