[Remote suggestions] Move the throttler into the Scheduler

components/ntp_snippets/remote/json_request.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_REMOTE_JSON_REQUEST_H_
 #define COMPONENTS_NTP_SNIPPETS_REMOTE_JSON_REQUEST_H_
 
 #include <memory>
 #include <string>
 #include <utility>
@@ skipping 17 matching lines @@
 
 namespace ntp_snippets {
 class UserClassifier;
 
 namespace internal {
 
 // Enumeration listing all possible outcomes for fetch attempts. Used for UMA
 // histograms, so do not change existing values. Insert new values at the end,
 // and update the histogram definition.
 enum class FetchResult {
-  SUCCESS,
-  DEPRECATED_EMPTY_HOSTS,
-  URL_REQUEST_STATUS_ERROR,
-  HTTP_ERROR,
-  JSON_PARSE_ERROR,
-  INVALID_SNIPPET_CONTENT_ERROR,
-  OAUTH_TOKEN_ERROR,
-  INTERACTIVE_QUOTA_ERROR,
-  NON_INTERACTIVE_QUOTA_ERROR,
-  RESULT_MAX
+  SUCCESS = 0,

[Ilya Sherman, 2017/02/27 19:32:26]

I'd suggest keeping a comment line like

  // DEPRECATED_EMPTY_HOSTS = 1,

to document what value used to be here, and to discourage a well-intentioned
project member from "helpfully fixing" this code in the future.  (Ditto for the
other two deprecated values).

+  URL_REQUEST_STATUS_ERROR = 2,
+  HTTP_ERROR = 3,
+  JSON_PARSE_ERROR = 4,
+  INVALID_SNIPPET_CONTENT_ERROR = 5,
+  OAUTH_TOKEN_ERROR = 6,
+  // Next available ID: 9 (due to some values being deprecated).
+  RESULT_MAX = 9
 };
 
 enum FetchAPI {
   CHROME_READER_API,
   CHROME_CONTENT_SUGGESTIONS_API,
 };
 
 // A single request to query remote suggestions. On success, the suggestions are
 // returned in parsed JSON form (base::Value).
 class JsonRequest : public net::URLFetcherDelegate {
@@ skipping 119 matching lines @@
   base::WeakPtrFactory<JsonRequest> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(JsonRequest);
 };
 
 }  // namespace internal
 
 }  // namespace ntp_snippets
 
 #endif  // COMPONENTS_NTP_SNIPPETS_REMOTE_JSON_REQUEST_H_