[sync] Upstream the Android ProfileSyncService

chrome/android/java/src/org/chromium/chrome/browser/identity/UniqueIdentificationGenerator.java

Index: chrome/android/java/src/org/chromium/chrome/browser/identity/UniqueIdentificationGenerator.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/identity/UniqueIdentificationGenerator.java b/chrome/android/java/src/org/chromium/chrome/browser/identity/UniqueIdentificationGenerator.java
new file mode 100644
index 0000000000000000000000000000000000000000..bbb6b67b9bf8d7632da77c45463b394015bd60c6
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/identity/UniqueIdentificationGenerator.java
@@ -0,0 +1,23 @@
+// Copyright 2013 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.
+
+package org.chromium.chrome.browser.identity;
+
+import javax.annotation.Nullable;
+
+/**
+ * Interface used for uniquely identifying an installation of Chrome. To get an instance you should
+ * use {@link UniqueIdentificationGeneratorFactory}.
+ */
+public interface UniqueIdentificationGenerator {
+    /**
+     * Creates a string that uniquely identifies this installation.
+     * <p/>
+     * If there is an error in generating the string, an empty string must be returned, not null.
+     *
+     * @param salt the salt to use for the unique ID.
+     * @return a unique ID. On failure to generate, it must return the empty string.
+     */
+    String getUniqueId(@Nullable String salt);
+}