Add hash to OFC pasteboard change detection

components/open_from_clipboard/fake_clipboard_recent_content.cc

 // Copyright 2015 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 "components/open_from_clipboard/fake_clipboard_recent_content.h"
 
 FakeClipboardRecentContent::FakeClipboardRecentContent()
     : content_age_(base::TimeDelta::Max()), suppress_content_(false) {}
 
 FakeClipboardRecentContent::~FakeClipboardRecentContent() {}
@@ skipping 10 matching lines @@
 }
 
 base::TimeDelta FakeClipboardRecentContent::GetClipboardContentAge() const {
   return content_age_;
 }
 
 void FakeClipboardRecentContent::SuppressClipboardContent() {
   suppress_content_ = true;
 }
 
+void FakeClipboardRecentContent::RecentURLDisplayed() {}
+
 void FakeClipboardRecentContent::SetClipboardContent(
     const GURL& url,
     base::TimeDelta content_age) {
   clipboard_content_ = url;
   content_age_ = content_age;
   suppress_content_ = false;
 }