[omnibox] launch on device head suggest on Desktop non-Incognito.

The variant to be launched: http://screenshot/6pp7qvc8gfMGyxm

Bug: 925072
Change-Id: I931f6a2432466d1b3692773256634aaad12d14dc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2578505Reviewed-by: Justin Donnelly <jdonnelly@chromium.org>
Commit-Queue: Ce Chen <cch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#835541}

components/omnibox/browser/omnibox_field_trial.cc

@@ -781,13 +781,18 @@ std::string OmniboxFieldTrial::OnDeviceHeadModelLocaleConstraint(
 }
 
 int OmniboxFieldTrial::OnDeviceHeadSuggestMaxScoreForNonUrlInput(
-    bool is_incognito,
-    const int default_score) {
+    bool is_incognito) {
+  const int kDefaultScore =
+#if defined(OS_ANDROID) || defined(OS_IOS)
+      99;
+#else
+      is_incognito ? 99 : 1000;
+#endif  // defined(OS_ANDROID) || defined(OS_IOS)
   return is_incognito
-             ? default_score
+             ? kDefaultScore
              : base::GetFieldTrialParamByFeatureAsInt(
                    omnibox::kOnDeviceHeadProviderNonIncognito,
-                   kOnDeviceHeadSuggestMaxScoreForNonUrlInput, default_score);
+                   kOnDeviceHeadSuggestMaxScoreForNonUrlInput, kDefaultScore);
 }
 
 int OmniboxFieldTrial::OnDeviceHeadSuggestDelaySuggestRequestMs(
@@ -814,9 +819,14 @@ int OmniboxFieldTrial::OnDeviceSearchProviderDefaultLoaderTimeoutMs(
 }
 
 std::string OmniboxFieldTrial::OnDeviceHeadSuggestDemoteMode() {
-  return base::GetFieldTrialParamValueByFeature(
+  std::string demote_mode = base::GetFieldTrialParamValueByFeature(
       omnibox::kOnDeviceHeadProviderNonIncognito,
       kOnDeviceHeadSuggestDemoteMode);
+#if !defined(OS_ANDROID) && !defined(OS_IOS)
+  if (demote_mode.empty())
+    demote_mode = "decrease-relevances";
+#endif  // !defined(OS_ANDROID) && !defined(OS_IOS)
+  return demote_mode;
 }
 
 bool OmniboxFieldTrial::ShouldRevealPathQueryRefOnHover() {

components/omnibox/browser/omnibox_field_trial.h

@@ -417,8 +417,7 @@ bool IsOnDeviceHeadSuggestEnabledForNonIncognito();
 bool IsOnDeviceHeadSuggestEnabledForAnyMode();
 // Functions can be used in both non-incognito and incognito.
 std::string OnDeviceHeadModelLocaleConstraint(bool is_incognito);
-int OnDeviceHeadSuggestMaxScoreForNonUrlInput(bool is_incognito,
-                                              const int default_score);
+int OnDeviceHeadSuggestMaxScoreForNonUrlInput(bool is_incognito);
 int OnDeviceSearchProviderDefaultLoaderTimeoutMs(bool is_incognito);
 int OnDeviceHeadSuggestDelaySuggestRequestMs(bool is_incognito);
 // Function only works in non-incognito when server suggestions are available.

components/omnibox/browser/on_device_head_provider.cc

@@ -30,7 +30,7 @@
 #include "third_party/metrics_proto/omnibox_input_type.pb.h"
 
 namespace {
-const int kBaseRelevance = 99;
+const int kBaseRelevanceForUrlInput = 99;
 const size_t kMaxRequestId = std::numeric_limits<size_t>::max() - 1;
 
 bool IsDefaultSearchProviderGoogle(
@@ -262,9 +262,9 @@ void OnDeviceHeadProvider::SearchDone(
 
     int relevance =
         params->input.type() == metrics::OmniboxInputType::URL
-            ? kBaseRelevance
+            ? kBaseRelevanceForUrlInput
             : OmniboxFieldTrial::OnDeviceHeadSuggestMaxScoreForNonUrlInput(
-                  client()->IsOffTheRecord(), kBaseRelevance);
+                  client()->IsOffTheRecord());
 
     for (const auto& item : params->suggestions) {
       matches_.push_back(BaseSearchProvider::CreateOnDeviceSearchSuggestion(

components/omnibox/common/omnibox_features.cc

@@ -36,12 +36,13 @@ const auto enabled_by_default_desktop_ios =
     base::FEATURE_ENABLED_BY_DEFAULT;
 #endif
 
-const auto enabled_by_default_android_ios =
-#if defined(OS_ANDROID) || defined(OS_IOS)
-    base::FEATURE_ENABLED_BY_DEFAULT;
-#else
-    base::FEATURE_DISABLED_BY_DEFAULT;
-#endif
+// Comment out this macro since it is currently not being used in this file.
+// const auto enabled_by_default_android_ios =
+// #if defined(OS_ANDROID) || defined(OS_IOS)
+//     base::FEATURE_ENABLED_BY_DEFAULT;
+// #else
+//     base::FEATURE_DISABLED_BY_DEFAULT;
+// #endif
 
 // Allows Omnibox to dynamically adjust number of offered suggestions to fill in
 // the space between Omnibox an the soft keyboard. The number of suggestions
@@ -253,7 +254,8 @@ const base::Feature kReactiveZeroSuggestionsOnNTPRealbox{
 const base::Feature kOnDeviceHeadProviderIncognito{
     "OmniboxOnDeviceHeadProviderIncognito", base::FEATURE_ENABLED_BY_DEFAULT};
 const base::Feature kOnDeviceHeadProviderNonIncognito{
-    "OmniboxOnDeviceHeadProviderNonIncognito", enabled_by_default_android_ios};
+    "OmniboxOnDeviceHeadProviderNonIncognito",
+    base::FEATURE_ENABLED_BY_DEFAULT};
 
 // If enabled, changes the way Google-provided search suggestions are scored by
 // the backend. Note that this Feature is only used for triggering a server-