Add spellcheck and word suggestion to the prediction service

mojo/services/prediction/public/interfaces/prediction.mojom

 // Copyright 2015 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.
 
 [DartPackage="mojo_services"]
 module prediction;
 
-struct Settings {
-  bool correction_enabled;
-  bool block_potentially_offensive;
-  bool space_aware_gesture_enabled;
+struct PrevWordInfo {
+        string word;
+        bool is_beginning_of_sentence;
 };
 
 struct PredictionInfo {
-  array<string> previous_words;
-  string current_word;
+        array<PrevWordInfo> previous_words;
+        string current_word;
 };
 
 interface PredictionService {
-  SetSettings(Settings settings);
-
   GetPredictionList(PredictionInfo prediction_info) => (array<string>? prediction_list);
 };