New snippets now replace old snippets and do not merge

components/ntp_snippets/ntp_snippets_database.h

 // 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.
 
 #ifndef COMPONENTS_NTP_SNIPPETS_NTP_SNIPPETS_DATABASE_H_
 #define COMPONENTS_NTP_SNIPPETS_NTP_SNIPPETS_DATABASE_H_
 
 #include <memory>
 #include <string>
+#include <utility>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/sequenced_task_runner.h"
 #include "components/leveldb_proto/proto_database.h"
 #include "components/ntp_snippets/ntp_snippet.h"
 
@@ skipping 31 matching lines @@
   // Loads all snippets from storage and passes them to |callback|.
   void LoadSnippets(const SnippetsCallback& callback);
 
   // Adds or updates the given snippet.
   void SaveSnippet(const NTPSnippet& snippet);
   // Adds or updates all the given snippets.
   void SaveSnippets(const NTPSnippet::PtrVector& snippets);
 
   // Deletes the snippet with the given ID, and its image.
   void DeleteSnippet(const std::string& snippet_id);
-  // Deletes all the given snippets (identified by their IDs) and their images.
+  // Deletes all the given snippets (identified by their IDs), not their images.
   void DeleteSnippets(const NTPSnippet::PtrVector& snippets);
 
   // Loads the image data for the snippet with the given ID and passes it to
   // |callback|. Passes an empty string if not found.
   void LoadImage(const std::string& snippet_id,
                  const SnippetImageCallback& callback);
 
   // Adds or updates the image data for the given snippet ID.
   void SaveImage(const std::string& snippet_id, const std::string& image_data);
 
   // Deletes the image data for the given snippet ID.
   void DeleteImage(const std::string& snippet_id);
+  // Deletes the image data for the given snippets (identified by their IDs).
+  void DeleteImages(const NTPSnippet::PtrVector& snippets);
 
  private:
   friend class NTPSnippetsDatabaseTest;
 
   using KeyEntryVector =
       leveldb_proto::ProtoDatabase<SnippetProto>::KeyEntryVector;
 
   using ImageKeyEntryVector =
       leveldb_proto::ProtoDatabase<SnippetImageProto>::KeyEntryVector;
 
@@ skipping 38 matching lines @@
   base::Closure error_callback_;
 
   base::WeakPtrFactory<NTPSnippetsDatabase> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(NTPSnippetsDatabase);
 };
 
 }  // namespace ntp_snippets
 
 #endif  // COMPONENTS_NTP_SNIPPETS_NTP_SNIPPETS_DATABASE_H_