Add validateOrigin() to the support library.

customtabs/src/android/support/customtabs/CustomTabsClient.java

Index: customtabs/src/android/support/customtabs/CustomTabsClient.java
diff --git a/customtabs/src/android/support/customtabs/CustomTabsClient.java b/customtabs/src/android/support/customtabs/CustomTabsClient.java
index 5d7bb9b040a31fb21e4c97ad07e7282216d17810..d53d3a25d386a672313b2d39df76102a560c4e32 100644
--- a/customtabs/src/android/support/customtabs/CustomTabsClient.java
+++ b/customtabs/src/android/support/customtabs/CustomTabsClient.java
@@ -29,6 +29,7 @@ import android.os.Looper;
 import android.os.RemoteException;
 import android.support.annotation.Nullable;
 import android.support.annotation.RestrictTo;
+import android.support.customtabs.CustomTabsService.Relation;
 import android.text.TextUtils;
 
 import java.util.ArrayList;
@@ -231,6 +232,20 @@ public class CustomTabsClient {
                     }
                 });
             }
+
+            @Override
+            public void onRelationshipValidationResult(
+                    final @Relation int relation, final Uri requestedOrigin, final boolean result,
+                    final @Nullable Bundle extras) throws RemoteException {
+                if (callback == null) return;
+                mHandler.post(new Runnable() {
+                    @Override
+                    public void run() {
+                        callback.onRelationshipValidationResult(
+                                relation, requestedOrigin, result, extras);
+                    }
+                });
+            }
         };
 
         try {