Omnibox: Add Field Trial to Create UWYT When Inlining

chrome/browser/autocomplete/history_url_provider.h

Index: chrome/browser/autocomplete/history_url_provider.h
diff --git a/chrome/browser/autocomplete/history_url_provider.h b/chrome/browser/autocomplete/history_url_provider.h
index 759146287170c7db0f50f59c31556b23a9136564..9c675fb2f36eed61e396e5b6aa48c973509c4b75 100644
--- a/chrome/browser/autocomplete/history_url_provider.h
+++ b/chrome/browser/autocomplete/history_url_provider.h
@@ -156,6 +156,12 @@ struct HistoryURLProviderParams {
   // this to.  See comments in DoAutocomplete().
   PromoteType promote_type;
 
+  // True if we should consider adding the what you typed match.  This
+  // decision is often already summarized in |promote_type| by whether it
+  // says to promote the what you typed match.  As such, this variable is
+  // only useful when |promote_type| is FRONT_HISTORY_MATCH.

[Peter Kasting, 2014/06/20 21:12:42]

Nit: I think this comment would be clearer as:

True if |what_you_typed_match| is eligible for display.  If this is true,
PromoteMatchesIfNecessary() may choose to place |what_you_typed_match| on
|matches_| even when |promote_type| is not WHAT_YOU_TYPED_MATCH.

[Mark P, 2014/06/23 22:23:12]

Yes, that is clearer.  Done.

+  bool have_what_you_typed_match;
+
   // Languages we should pass to gfx::GetCleanStringFromUrl.
   std::string languages;
 
@@ -245,8 +251,10 @@ class HistoryURLProvider : public HistoryProvider {
 
   // May promote either the what you typed match or first history match in
   // params->matches to the front of |matches_|, depending on the value of
-  // params->promote_type.
-  void PromoteMatchIfNecessary(const HistoryURLProviderParams& params);
+  // params->promote_type.  Also, depending on a field trial state, if it
+  // promotes the first history match, it may decide to append the what you
+  // typed matche immediately after.

[Peter Kasting, 2014/06/20 21:12:42]

Nit: How about:

May promote the what you typed match, the first history match, or both to the
front of |matches_|, depending on the values of params->promote_type and
params->have_what_you_typed_match.

(I don't think we need to mention field trial state here as this isn't meant to
be an exhaustive guide, but if you want to, you could add ", as well as field
trial state." to the end.)

[Mark P, 2014/06/23 22:23:12]

Okay, omitting the mention of the field trial seems reasonable.  Took your
comment with a minor edit (to mention params->matches).

+  void PromoteMatchesIfNecessary(const HistoryURLProviderParams& params);
 
   // Dispatches the results to the autocomplete controller. Called on the
   // main thread by ExecuteWithDB when the results are available.