Omnibox: Prevent Asynchronous Suggestions from Changing Default Match

components/autocomplete/search_suggestion_parser.h

Index: components/autocomplete/search_suggestion_parser.h
diff --git a/components/autocomplete/search_suggestion_parser.h b/components/autocomplete/search_suggestion_parser.h
index 264700ef8ebcc1921fb544a703140dadf8f9e39c..37dab517620d775cc83dafade4f2c0d6b47b1a70 100644
--- a/components/autocomplete/search_suggestion_parser.h
+++ b/components/autocomplete/search_suggestion_parser.h
@@ -54,6 +54,13 @@ class SearchSuggestionParser {
     AutocompleteMatchType::Type type() const { return type_; }
     int relevance() const { return relevance_; }
     void set_relevance(int relevance) { relevance_ = relevance; }
+    bool never_allowed_to_be_default_match() const {
+      return never_allowed_to_be_default_match_;
+    }
+    void set_never_allowed_to_be_default_match(
+        bool never_allowed_to_be_default_match) {
+      never_allowed_to_be_default_match_ = never_allowed_to_be_default_match;
+    }
 
     bool relevance_from_server() const { return relevance_from_server_; }
     void set_relevance_from_server(bool relevance_from_server) {
@@ -90,6 +97,11 @@ class SearchSuggestionParser {
     // there.
     bool relevance_from_server_;
 
+    // If true, this result should never be allowed to be the default match.

[msw, 2014/08/14 02:57:23]

Hmm, seems like this identifier and the relevant code could be a bit clearer if
this were |received_since_last_keystroke_|, always set true on receipt, and set
to false for those results which survive the next keystroke's SortAndCull (or
whatever the corresponding result/match cleanup for re-use is called nowadays).

[Mark P, 2014/08/15 00:05:56]

Done (received_after_last_keystroke).  I agree that this makes the explanation
of what's going on clearer.
Done.
Now the logic to has moved from Start() (when minimal_changes is false) to
RemoveAllStaleResults(), which I renamed to RemoveOrReviseOldResults().

+    // This field is ignored for verbatim results; those are regardless
+    // always allowed to be the default match.
+    bool never_allowed_to_be_default_match_;
+
     // Optional deletion URL provided with suggestions. Fetching this URL
     // should result in some reasonable deletion behaviour on the server,
     // e.g. deleting this term out of a user's server-side search history.
@@ -254,9 +266,6 @@ class SearchSuggestionParser {
 
     // URLs of any images in Answers results.
     std::vector<GURL> answers_image_urls;
-
-   private:
-    DISALLOW_COPY_AND_ASSIGN(Results);

[msw, 2014/08/14 02:57:23]

Why are you removing this? To allow the assignment of |default_results_ =
orig_default_results_;|, etc.? I think that's unnecessary in my suggested
feature implementation. This deserved an explicit CL description comment, or at
least a CL review comment explanation... Copying is bad, m'kay? :)

[Mark P, 2014/08/15 00:05:56]

Restored.  I explained why I did this in a previous e-mail.  With my new
approach, this is not necessary.

   };
 
   // Extracts JSON data fetched by |source| and converts it to UTF-8.