Add context menu when long press on a reading list entry

ios/chrome/browser/ui/util/pasteboard_util.mm

+// Copyright 2017 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.
+
+#import "ios/chrome/browser/ui/util/pasteboard_util.h"
+
+#import <MobileCoreServices/MobileCoreServices.h>
+#import <UIKit/UIKit.h>
+
+#include "base/strings/sys_string_conversions.h"
+#import "net/base/mac/url_conversions.h"
+#include "url/gurl.h"
+
+void StoreURLInPasteboard(const GURL& URL) {
+  DCHECK(URL.is_valid());
+  NSData* plainText = [base::SysUTF8ToNSString(URL.spec())
+      dataUsingEncoding:NSUTF8StringEncoding];
+  NSDictionary* copiedItem = @{
+    (NSString*)kUTTypeURL : net::NSURLWithGURL(URL),
+    (NSString*)kUTTypeUTF8PlainText : plainText,
+  };
+  [[UIPasteboard generalPasteboard] setItems:@[ copiedItem ]];
+}