Java side of purging BookmarkId from offline pages

chrome/android/java/src/org/chromium/chrome/browser/offlinepages/ClientId.java

Index: chrome/android/java/src/org/chromium/chrome/browser/offlinepages/ClientId.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/offlinepages/ClientId.java b/chrome/android/java/src/org/chromium/chrome/browser/offlinepages/ClientId.java
new file mode 100644
index 0000000000000000000000000000000000000000..dacfa4906b49b37829230ff0a5876535d3545161
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/offlinepages/ClientId.java
@@ -0,0 +1,51 @@
+// 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.
+
+package org.chromium.chrome.browser.offlinepages;
+
+import org.chromium.components.bookmarks.BookmarkId;
+
+/**
+ * Object to hold a client identifier for an offline page.
+ */
+public class ClientId {
+    private String mNamespace;
+    private String mId;
+
+    public ClientId(String namespace, String id) {
+        mNamespace = namespace;
+        mId = id;
+    }
+
+    public String getNamespace() {
+        return mNamespace;
+    }
+
+    public String getId() {
+        return mId;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (o instanceof ClientId) {
+            ClientId otherId = (ClientId) o;
+            return otherId.getNamespace().equals(mNamespace) && otherId.getId().equals(mId);
+        }
+        return false;
+    }
+
+    @Override
+    public int hashCode() {
+        return (mNamespace + ":" + mId).hashCode();
+    }
+
+    /**
+     * Create a client id for a bookmark
+     * @param id The bookmark id to wrap.
+     * @return A {@link ClientId} that represents this BookmarkId.
+     */
+    public static ClientId createClientIdForBookmarkId(BookmarkId id) {
+        return new ClientId(OfflinePageBridge.BOOKMARK_NAMESPACE, id.toString());
+    }
+}