Added UnguessableToken.java .

base/android/jni_unguessable_token.cc

+// 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.
+
+#include "base/android/jni_unguessable_token.h"
+
+#include "jni/UnguessableToken_jni.h"
+
+namespace base {
+namespace android {
+
+ScopedJavaLocalRef<jobject> CreateJavaUnguessableToken(
+    JNIEnv* env,
+    const base::UnguessableToken& token) {
+  return Java_UnguessableToken_create(env, token.GetHighForSerialization(),

[tguilbert, 2016/11/02 23:31:50]

Can you add a DCHECK(token) here? One of the goals of UnguessableToken was to
prevent developers from accidentally not initializing their tokens before their
use.

[liberato (no reviews please), 2016/11/03 15:42:30]

Done.

+                                      token.GetLowForSerialization());
+}
+
+base::UnguessableToken ConvertFromJavaUnguessableToken(
+    JNIEnv* env,
+    const JavaRef<jobject>& token) {
+  const uint64_t high =
+      Java_UnguessableToken_getHighForSerialization(env, token);
+  const uint64_t low = Java_UnguessableToken_getLowForSerialization(env, token);

[tguilbert, 2016/11/02 23:31:50]

Can you add a DCHECK to make sure the token that was created is not empty?

[liberato (no reviews please), 2016/11/03 15:42:30]

Done.

+  return base::UnguessableToken::Deserialize(high, low);
+}
+
+}  // namespace android
+}  // namespace base