[NTP Snippets] Persist the set of snippets in a pref

components/ntp_snippets/ntp_snippet.h

Index: components/ntp_snippets/ntp_snippet.h
diff --git a/components/ntp_snippets/ntp_snippet.h b/components/ntp_snippets/ntp_snippet.h
index 6dd2ad045bc64ab617cf2b893284aed0cd6ce09f..daa1d52fa3971a25a8af52d05e790992520851a8 100644
--- a/components/ntp_snippets/ntp_snippet.h
+++ b/components/ntp_snippets/ntp_snippet.h
@@ -1,6 +1,7 @@
 // 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.
+
 #ifndef COMPONENTS_NTP_SNIPPETS_NTP_SNIPPET_H_
 #define COMPONENTS_NTP_SNIPPETS_NTP_SNIPPET_H_
 
@@ -29,9 +30,11 @@ class NTPSnippet {
   // dictionary doesn't contain at least a url. The keys in the dictionary are
   // expected to be the same as the property name, with exceptions documented in
   // the property comment.
-  static scoped_ptr<NTPSnippet> NTPSnippetFromDictionary(
+  static scoped_ptr<NTPSnippet> CreateFromDictionary(
       const base::DictionaryValue& dict);
 
+  scoped_ptr<base::DictionaryValue> ToDictionary() const;
+
   // URL of the page described by this snippet.
   const GURL& url() const { return url_; }
 
@@ -54,15 +57,15 @@ class NTPSnippet {
   void set_snippet(const std::string& snippet) { snippet_ = snippet; }
 
   // Link to an image representative of the content. Do not fetch this image
-  // directly. If initialized by NTPSnippetFromDictionary() the relevant key is
-  // 'thumbnailURL'
+  // directly. If initialized by CreateFromDictionary() the relevant key is
+  // 'thumbnailUrl'
   const GURL& salient_image_url() const { return salient_image_url_; }
   void set_salient_image_url(const GURL& salient_image_url) {
     salient_image_url_ = salient_image_url;
   }
 
   // When the page pointed by this snippet was published.  If initialized by
-  // NTPSnippetFromDictionary() the relevant key is 'creationTimestampSec'
+  // CreateFromDictionary() the relevant key is 'creationTimestampSec'
   const base::Time& publish_date() const { return publish_date_; }
   void set_publish_date(const base::Time& publish_date) {
     publish_date_ = publish_date;