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.
 
 module prediction;
 
-struct Settings {
-  bool correction_enabled;
-  bool block_potentially_offensive;
-  bool space_aware_gesture_enabled;
-};
-
 struct PredictionInfo {
-  array<string> previous_words;
-  string current_word;
+        array<string> previous_words;
+        array<bool> are_beginning_of_sentence;  

[APW, 2015/07/23 18:02:15]

You should make a struct that has a string and bool and then have an array of
those here.  That would make the api clearer.

Also, do you need to know if the current work is the beginning of a sentence?

[riajiang, 2015/07/31 02:13:04]

Done.

I don't think we need that to search for word suggestions. I use current_word[0]
only after got back all the suggestions to check if I need to make the first
letter upper case. 

[APW, 2015/07/31 21:49:15]

What do you use the other is_beginning_of_sentence's for then?

+        string current_word;
 };
 
 interface PredictionService {
-  SetSettings(Settings settings);
-
   GetPredictionList(PredictionInfo prediction_info) => (array<string>? prediction_list);
 };