Omnibox: Create Disable-Inlining Experiment

chrome/browser/autocomplete/autocomplete_result.cc

Index: chrome/browser/autocomplete/autocomplete_result.cc
diff --git a/chrome/browser/autocomplete/autocomplete_result.cc b/chrome/browser/autocomplete/autocomplete_result.cc
index b4637f67a0b9ec77c44a5a48db3156e87c99ecde..a65ca2b8a880ab22a7f49678dd149d11278bdfbd 100644
--- a/chrome/browser/autocomplete/autocomplete_result.cc
+++ b/chrome/browser/autocomplete/autocomplete_result.cc
@@ -8,6 +8,7 @@
 #include <iterator>
 
 #include "base/logging.h"
+#include "base/metrics/histogram.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/autocomplete/autocomplete_input.h"
 #include "chrome/browser/autocomplete/autocomplete_match.h"
@@ -92,6 +93,18 @@ bool DestinationSort::operator()(const AutocompleteMatch& elem1,
   return elem1.stripped_destination_url < elem2.stripped_destination_url;
 }
 
+// Returns true if |match| is allowed to the default match taking into account
+// whether we're supposed to (and able to) demote all matches with inline
+// autocompletions.
+bool AllowedToBeDefaultMatchAccountingForDisableInliningExperiment(
+    const AutocompleteMatch& match,
+    const bool has_legal_default_match_without_completion) {
+  return match.allowed_to_be_default_match &&
+      (!OmniboxFieldTrial::DisableInlining() ||
+       !has_legal_default_match_without_completion ||
+       match.inline_autocompletion.empty());
+}
+
 };  // namespace
 
 // static
@@ -177,16 +190,37 @@ void AutocompleteResult::SortAndCull(const AutocompleteInput& input,
   DedupMatchesByDestination(input.current_page_classification(), true,
                             &matches_);
 
+  // If the result set has at least one legal default match without an inline
+  // autocompletion, then in the disable inlining experiment it will be okay
+  // to demote all matches with inline autocompletions.  On the other hand, if
+  // the experiment is active but there is no legal match without an inline
+  // autocompletion, then we'll pretend the experiment is not active and not
+  // demote the matches with an inline autocompletion.  In other words, an
+  // alternate name for this variable is
+  // allowed_to_demote_matches_with_inline_autocompletion.
+  bool has_legal_default_match_without_completion = false;
+  for (AutocompleteResult::iterator it = matches_.begin();
+       (it != matches_.end()) && !has_legal_default_match_without_completion;
+       ++it) {
+    if (it->allowed_to_be_default_match && it->inline_autocompletion.empty())
+      has_legal_default_match_without_completion = true;
+  }
+  UMA_HISTOGRAM_BOOLEAN("Omnibox.HasLegalDefaultMatchWithoutCompletion",
+                        has_legal_default_match_without_completion);
+
   // Sort and trim to the most relevant kMaxMatches matches.
   size_t max_num_matches = std::min(kMaxMatches, matches_.size());
   CompareWithDemoteByType comparing_object(input.current_page_classification());
   std::sort(matches_.begin(), matches_.end(), comparing_object);
-  if (!matches_.empty() && !matches_.begin()->allowed_to_be_default_match) {
+  if (!matches_.empty() &&
+      !AllowedToBeDefaultMatchAccountingForDisableInliningExperiment(
+          *matches_.begin(), has_legal_default_match_without_completion)) {
     // Top match is not allowed to be the default match.  Find the most
     // relevant legal match and shift it to the front.
     for (AutocompleteResult::iterator it = matches_.begin() + 1;
          it != matches_.end(); ++it) {
-      if (it->allowed_to_be_default_match) {
+      if (AllowedToBeDefaultMatchAccountingForDisableInliningExperiment(
+              *it, has_legal_default_match_without_completion)) {
         std::rotate(matches_.begin(), it, it + 1);
         break;
       }