[AiS] Add prefetching for Answers images.

chrome/browser/autocomplete/base_search_provider.h

 // Copyright 2014 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.
 //
 // This class contains common functionality for search-based autocomplete
 // providers. Search provider and zero suggest provider both use it for common
 // functionality.
 
 #ifndef CHROME_BROWSER_AUTOCOMPLETE_BASE_SEARCH_PROVIDER_H_
 #define CHROME_BROWSER_AUTOCOMPLETE_BASE_SEARCH_PROVIDER_H_
@@ skipping 10 matching lines @@
 #include "chrome/browser/autocomplete/autocomplete_provider.h"
 #include "net/url_request/url_fetcher_delegate.h"
 
 class AutocompleteProviderListener;
 class GURL;
 class Profile;
 class SuggestionDeletionHandler;
 class TemplateURL;
 
 namespace base {
+class DictionaryValue;
 class ListValue;
 class Value;
 }
 
 // Base functionality for receiving suggestions from a search engine.
 // This class is abstract and should only be used as a base for other
 // autocomplete providers utilizing its functionality.
 class BaseSearchProvider : public AutocompleteProvider,
                            public net::URLFetcherDelegate {
  public:
@@ skipping 386 matching lines @@
                      MatchMap* map);
 
   // Parses results from the suggest server and updates the appropriate suggest
   // and navigation result lists in |results|. |is_keyword_result| indicates
   // whether the response was received from the keyword provider.
   // Returns whether the appropriate result list members were updated.
   bool ParseSuggestResults(const base::Value& root_val,
                            bool is_keyword_result,
                            Results* results);
 
+  // Prefetches any images in Answers results.
+  void PrefetchAnswersImages(const base::DictionaryValue* answers_json);
+
   // Called at the end of ParseSuggestResults to rank the |results|.
   virtual void SortResults(bool is_keyword,
                            const base::ListValue* relevances,
                            Results* results);
 
   // Optionally, cache the received |json_data| and return true if we want
   // to stop processing results at this point. The |parsed_data| is the parsed
   // version of |json_data| used to determine if we received an empty result.
   virtual bool StoreSuggestionResponse(const std::string& json_data,
                                        const base::Value& parsed_data);
@@ skipping 74 matching lines @@
 
   // True if this provider's results are being displayed in the app list. By
   // default this is false, meaning that the results will be shown in the
   // omnibox.
   bool in_app_list_;
 
   DISALLOW_COPY_AND_ASSIGN(BaseSearchProvider);
 };
 
 #endif  // CHROME_BROWSER_AUTOCOMPLETE_BASE_SEARCH_PROVIDER_H_