ntp_snippets: default to staging API on dev/canary

components/ntp_snippets/remote/remote_suggestions_fetcher.h

Index: components/ntp_snippets/remote/remote_suggestions_fetcher.h
diff --git a/components/ntp_snippets/remote/remote_suggestions_fetcher.h b/components/ntp_snippets/remote/remote_suggestions_fetcher.h
index dc023dc705ab581b30c77acf80390d6530202f8c..448cfb8da7034817868b9bf324062552810fee1d 100644
--- a/components/ntp_snippets/remote/remote_suggestions_fetcher.h
+++ b/components/ntp_snippets/remote/remote_suggestions_fetcher.h
@@ -36,6 +36,10 @@ namespace ntp_snippets {
 
 class UserClassifier;
 
+// Returns the appropriate API endpoint for the fetcher, in consideration of
+// the channel and variation parameters.
+std::string GetFetchEndpoint(bool is_stable_or_beta_channel);
+
 // TODO(tschumann): BuildArticleCategoryInfo() and BuildRemoteCategoryInfo()
 // don't really belong into this library. However, as the fetcher is
 // providing this data for server-defined remote sections it's a good starting
@@ -83,6 +87,7 @@ class RemoteSuggestionsFetcher : public OAuth2TokenService::Consumer,
       PrefService* pref_service,
       translate::LanguageModel* language_model,
       const ParseJSONCallback& parse_json_callback,
+      const std::string& api_endpoint,
       const std::string& api_key,
       const UserClassifier* user_classifier);
   ~RemoteSuggestionsFetcher() override;