[NTP Snippets] Persist snippets in a LevelDB instead of prefs

components/ntp_snippets.gypi

Index: components/ntp_snippets.gypi
diff --git a/components/ntp_snippets.gypi b/components/ntp_snippets.gypi
index 215b2ce305b2c869fb9cc7f6752bcc5cddaa0585..6a0e06e71061772e658acf9480b166b9fecabe61 100644
--- a/components/ntp_snippets.gypi
+++ b/components/ntp_snippets.gypi
@@ -20,6 +20,7 @@
         'data_use_measurement_core',
         'image_fetcher',
         'keyed_service_core',
+        'leveldb_proto',
         'prefs/prefs.gyp:prefs',
         'signin_core_browser',
         'suggestions',
@@ -31,6 +32,8 @@
         'ntp_snippets/ntp_snippet.h',
         'ntp_snippets/ntp_snippets_constants.cc',
         'ntp_snippets/ntp_snippets_constants.h',
+        'ntp_snippets/ntp_snippets_database.cc',
+        'ntp_snippets/ntp_snippets_database.h',
         'ntp_snippets/ntp_snippets_fetcher.cc',
         'ntp_snippets/ntp_snippets_fetcher.h',
         'ntp_snippets/ntp_snippets_scheduler.h',
@@ -38,9 +41,15 @@
         'ntp_snippets/ntp_snippets_service.h',
         'ntp_snippets/pref_names.cc',
         'ntp_snippets/pref_names.h',
+        'ntp_snippets/proto/ntp_snippets.proto',
         'ntp_snippets/switches.cc',
         'ntp_snippets/switches.h',
       ],
+      'variables': {
+        'proto_in_dir': 'ntp_snippets/proto',
+        'proto_out_dir': 'components/ntp_snippets/proto',
+      },
+      'includes': [ '../build/protoc.gypi' ],
     },
   ],
 }