[NTP Snippets] Shut down the service on database failure

components/ntp_snippets/ntp_snippets_database.h

Index: components/ntp_snippets/ntp_snippets_database.h
diff --git a/components/ntp_snippets/ntp_snippets_database.h b/components/ntp_snippets/ntp_snippets_database.h
index 336dad02c3d4f8447200a18840d34481b2bcba47..983166235f0ca70265f66149e3ae6c9b6aa842d5 100644
--- a/components/ntp_snippets/ntp_snippets_database.h
+++ b/components/ntp_snippets/ntp_snippets_database.h
@@ -41,6 +41,13 @@ class NTPSnippetsDatabase {
   // initialization finishes), but no updates are allowed.
   bool IsInitialized() const;
 
+  // Returns whether the database is in an (unrecoverable) error state. If this
+  // is true, the database must not be used anymore
+  bool IsErrorState() const;
+
+  // Set a callback to be called when the database enters an error state.
+  void SetErrorCallback(const base::Closure& error_callback);
+
   // Loads all snippets from storage and passes them to |callback|.
   void LoadSnippets(const SnippetsCallback& callback);
 
@@ -88,6 +95,8 @@ class NTPSnippetsDatabase {
                              std::unique_ptr<SnippetImageProto> entry);
   void OnImageDatabaseSaved(bool success);
 
+  void OnDatabaseError();
+
   void ProcessPendingLoads();
 
   void LoadSnippetsImpl(const SnippetsCallback& callback);
@@ -100,8 +109,6 @@ class NTPSnippetsDatabase {
   void DeleteImagesImpl(
       std::unique_ptr<std::vector<std::string>> keys_to_remove);
 
-  void ResetDatabases();
-
   std::unique_ptr<leveldb_proto::ProtoDatabase<SnippetProto>> database_;
   bool database_initialized_;
   std::vector<SnippetsCallback> pending_snippets_callbacks_;
@@ -112,6 +119,8 @@ class NTPSnippetsDatabase {
   std::vector<std::pair<std::string, SnippetImageCallback>>
       pending_image_callbacks_;
 
+  base::Closure error_callback_;

[Bernhard Bauer, 2016/06/20 17:37:46]

At some point you could think about switching to a client interface instead of
having multiple callbacks and lists thereof.

[Marc Treib, 2016/06/21 08:27:48]

Hm, true. I generally like explicit callbacks because it's often convenient for
the client to bind their own parameters to them, but maybe the point has come to
switch over to a client interface here...

+
   base::WeakPtrFactory<NTPSnippetsDatabase> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(NTPSnippetsDatabase);