Allow non default prefetch suggestions to be prefetched

chrome/browser/ui/omnibox/omnibox_controller.cc

Index: chrome/browser/ui/omnibox/omnibox_controller.cc
diff --git a/chrome/browser/ui/omnibox/omnibox_controller.cc b/chrome/browser/ui/omnibox/omnibox_controller.cc
index 29d27d7e01d42b142f9e723ed68754e68b31e732..0db08853e017dce0d0ee9cbd5ca69d3b89be4b43 100644
--- a/chrome/browser/ui/omnibox/omnibox_controller.cc
+++ b/chrome/browser/ui/omnibox/omnibox_controller.cc
@@ -30,30 +30,39 @@ namespace {
 //
 // 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.
+// highly or if allow_prefetch_non_default_match field trial is enabled, 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.
+// If the allow_prefetch_non_default_match field trial is enabled we return the

[kmadhusu, 2014/06/18 17:07:38]

s/allow_prefetch_.../kAllowPrefetchNonDefaultMatch/g

[sidharthms, 2014/06/18 22:45:22]

Done.

+// prefetch suggestion even if it is not the default match. Otherwise 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) {
-  // If the default match should be prefetched, do that.
-  const AutocompleteResult::const_iterator default_match(
-      result.default_match());
-  if ((default_match != result.end()) &&
-      SearchProvider::ShouldPrefetch(*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() ||
-       result.TopMatchIsStandaloneVerbatimMatch()) &&
-      (result.size() > 1) &&
-      SearchProvider::ShouldPrefetch(result.match_at(1)))
-    return &result.match_at(1);
-
+  if (chrome::ShouldAllowPrefetchNonDefaultMatch()) {
+    const AutocompleteResult::const_iterator prefetch_match = std::find_if(
+        result.begin(), result.end(), SearchProvider::ShouldPrefetch);
+    if (prefetch_match != result.end())

[kmadhusu, 2014/06/18 17:07:38]

nit: You can use a ternary operator here and remove the else block. 

return prefetch_match != result.end() ? &(*prefetch_match) : NULL;

[sidharthms, 2014/06/18 22:45:22]

Done.

+      return &(*prefetch_match);

[kmadhusu, 2014/06/18 17:07:38]

As you said yesterday, when we type "ya" we are submitting a prefetch request
for the search query "youtube". We should figure out why that's happening. (FYI)
When we sent a request to fetch results for "youtube", "youtube" was not
displayed in the suggestions list. 

[sidharthms, 2014/06/18 22:45:22]

Done.

+  } else {
+    // If the default match should be prefetched, do that.
+    const AutocompleteResult::const_iterator default_match(
+        result.default_match());
+    if ((default_match != result.end()) &&
+        SearchProvider::ShouldPrefetch(*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() ||
+         result.TopMatchIsStandaloneVerbatimMatch()) &&
+        (result.size() > 1) &&
+        SearchProvider::ShouldPrefetch(result.match_at(1)))
+      return &result.match_at(1);
+  }
   return NULL;
 }