Modified GetMatchToPrefetch() to return a valid match for prefetching even when hide_verbatim flag i

chrome/browser/ui/omnibox/omnibox_controller.cc

 // Copyright 2013 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.
 
 #include "chrome/browser/ui/omnibox/omnibox_controller.h"
 
 #include "base/metrics/histogram.h"
 #include "chrome/browser/autocomplete/autocomplete_classifier.h"
 #include "chrome/browser/autocomplete/autocomplete_match.h"
 #include "chrome/browser/autocomplete/search_provider.h"
@@ skipping 13 matching lines @@
 #include "extensions/common/constants.h"
 #include "ui/gfx/rect.h"
 
 namespace {
 
 // Returns the AutocompleteMatch that the InstantController should prefetch, if
 // any.
 //
 // The SearchProvider may mark some suggestions to be prefetched based on
 // instructions from the suggest server. If such a match ranks sufficiently
-// highly, we'll return it. We only care about matches that are the default or
-// else the very first entry in the dropdown (which can happen for non-default
-// matches only if we're hiding a top verbatim match); for other matches, we
-// think the likelihood of the user selecting them is low enough that
-// prefetching isn't worth doing.
+// highly, we'll return it.
+//
+// We only care about matches that are the default or the very first entry in
+// the dropdown (which can happen for non-default matches only if we're hiding
+// a top verbatim match) or the second entry in the dropdown (which can happen
+// for non-default matches when a top verbatim match is shown); for other
+// matches, we think the likelihood of the user selecting them is low enough
+// that prefetching isn't worth doing.
 const AutocompleteMatch* GetMatchToPrefetch(const AutocompleteResult& result) {
   const AutocompleteResult::const_iterator default_match(
       result.default_match());
   if (default_match == result.end())
     return NULL;
 
   if (SearchProvider::ShouldPrefetch(*default_match))
     return &(*default_match);
 
-  return (result.ShouldHideTopMatch() && (result.size() > 1) &&
-      SearchProvider::ShouldPrefetch(result.match_at(1))) ?
-          &result.match_at(1) : NULL;
+  return ((result.ShouldHideTopMatch() ||
+              result.TopMatchIsVerbatimAndHasNoConsecutiveVerbatimMatches()) &&
+          (result.size() > 1) &&
+          SearchProvider::ShouldPrefetch(result.match_at(1))) ?
+              &result.match_at(1) : NULL;

[Peter Kasting, 2013/12/17 23:47:34]

Nit: Indenting here is inconsistent; sometimes you're indenting even with the
inside of the parens, other times 4.  Do this:

{
  // If the default match should be prefetched, do that.
  if ((result.default_match() != result.end()) &&
      SearchProvider::ShouldPrefetch(*result.default_match()))
    return &(*default_match);

  // Otherwise, if the top match is a verbatim match and the very next match is
  // prefetchable, fetch that.
  if ((result.ShouldHideTopMatch() || TopMatchIsStandaloneVerbatimMatch()) &&
      (result.size() > 1) && SearchProvider::ShouldPrefetch(result.match_at(1)))
    return &result.match_at(1);

  return NULL;
}

Note that this allows the second conditional to run when there is no default
match; this seems theoretically more like what you actually want, even though it
will have no practical effect.

This also adds some comments.  Writing them made me question whether we really
want to call TopMatchIsStandaloneVerbatimMatch() here.  Are you sure we don't
just want to always prefetch any match in position 1 or 2?

[kmadhusu, 2013/12/18 23:26:08]

Fixed indentation. 
Lets start with the conservative approach and expand later if  things work well.

 }
 
 }  // namespace
 
 OmniboxController::OmniboxController(OmniboxEditModel* omnibox_edit_model,
                                      Profile* profile)
     : omnibox_edit_model_(omnibox_edit_model),
       profile_(profile),
       popup_(NULL),
       autocomplete_controller_(new AutocompleteController(profile, this,
@@ skipping 86 matching lines @@
     if (profile_->GetNetworkPredictor()) {
       profile_->GetNetworkPredictor()->AnticipateOmniboxUrl(
           match.destination_url,
           predictors::AutocompleteActionPredictor::IsPreconnectable(match));
     }
     // We could prefetch the alternate nav URL, if any, but because there
     // can be many of these as a user types an initial series of characters,
     // the OS DNS cache could suffer eviction problems for minimal gain.
   }
 }