Add validateOrigin() to the support library.

customtabs/src/android/support/customtabs/CustomTabsSession.java

Index: customtabs/src/android/support/customtabs/CustomTabsSession.java
diff --git a/customtabs/src/android/support/customtabs/CustomTabsSession.java b/customtabs/src/android/support/customtabs/CustomTabsSession.java
index a0df820efb9a0fa986cd7a5fed71ea6aa5f565fe..5275c220fe5ca50d939107e5f98f7ae80a4e4ee8 100644
--- a/customtabs/src/android/support/customtabs/CustomTabsSession.java
+++ b/customtabs/src/android/support/customtabs/CustomTabsSession.java
@@ -25,6 +25,7 @@ import android.os.IBinder;
 import android.os.RemoteException;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
+import android.support.customtabs.CustomTabsService.Relation;
 import android.support.customtabs.CustomTabsService.Result;
 import android.support.customtabs.CustomTabsSessionToken.DummyCallback;
 import android.view.View;
@@ -197,6 +198,33 @@ public final class CustomTabsSession {
         }
     }
 
+    /**
+     * Request to validate a relationship between the application and an origin.
+     *
+     * If this method returns true, the validation result will be provided through
+     * {@link CustomTabsCallback#onRelationshipValidationResult(int, Uri, boolean, Bundle)}.
+     * Otherwise the request didn't succeed. The client must call
+     * {@link CustomTabsClient#warmup(long)} before this.
+     *
+     * @param relation Relation to check, must be one of the {@code CustomTabsService#RELATION_* }
+     *                 constants.
+     * @param origin Origin.
+     * @param extras Reserved for future use.
+     * @return true if the request has been submitted successfully.
+     */
+    public boolean validateRelationship(@Relation int relation, Uri origin,
+                                        @Nullable Bundle extras) {
+        if (relation < CustomTabsService.RELATION_USE_AS_ORIGIN ||
+                relation > CustomTabsService.RELATION_HANDLE_ALL_URLS) {
+            return false;
+        }
+        try {
+            return mService.validateRelationship(mCallback, relation, origin, extras);
+        } catch (RemoteException e) {
+            return false;
+        }
+    }
+
     /* package */ IBinder getBinder() {
         return mCallback.asBinder();
     }