Make Clipboard.java a singleton pattern.

chrome/android/java/src/org/chromium/chrome/browser/history/HistoryManager.java

 // 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.history;
 
 import android.app.Activity;
 import android.app.ActivityManager;
 import android.content.ComponentName;
 import android.content.Context;
@@ skipping 164 matching lines @@
 
         if (item.getItemId() == R.id.close_menu_id && isDisplayedInSeparateActivity()) {
             mActivity.finish();
             return true;
         } else if (item.getItemId() == R.id.selection_mode_open_in_new_tab) {
             openItemsInNewTabs(mSelectionDelegate.getSelectedItems(), false);
             mSelectionDelegate.clearSelection();
             return true;
         } else if (item.getItemId() == R.id.selection_mode_copy_link) {
             recordUserActionWithOptionalSearch("CopyLink");
-            Clipboard clipboard = new Clipboard(mActivity);
-            clipboard.setText(mSelectionDelegate.getSelectedItems().get(0).getUrl());
+            Clipboard.getInstance().setText(mSelectionDelegate.getSelectedItems().get(0).getUrl());
             mSelectionDelegate.clearSelection();
             Snackbar snackbar = Snackbar.make(mActivity.getString(R.string.copied), this,
                     Snackbar.TYPE_NOTIFICATION, Snackbar.UMA_HISTORY_LINK_COPIED);
             ((SnackbarManageable) mActivity).getSnackbarManager().showSnackbar(snackbar);
             return true;
         } else if (item.getItemId() == R.id.selection_mode_open_in_incognito) {
             openItemsInNewTabs(mSelectionDelegate.getSelectedItems(), true);
             mSelectionDelegate.clearSelection();
             return true;
         } else if (item.getItemId() == R.id.selection_mode_delete_menu_id) {
@@ skipping 232 matching lines @@
     @Override
     public void onAction(Object actionData) {
         // Handler for the link copied snackbar. Do nothing.
     }
 
     @Override
     public void onDismissNoAction(Object actionData) {
         // Handler for the link copied snackbar. Do nothing.
     }
 }