[omnibox] Make On Device Head Suggest available on Desktop

Works great on my desktop. Needs further testing though.

Making this flag available on Desktop.

Bug: 925072
Change-Id: I77ced4f1b72694db389ba528b9f1d3cd648bd58d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1775221Reviewed-by: Justin Donnelly <jdonnelly@chromium.org>
Commit-Queue: Tommy Li <tommycli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#692189}

chrome/browser/about_flags.cc

@@ -2682,11 +2682,6 @@ const FeatureEntry kFeatureEntries[] = {
 #endif  // defined(OS_WIN)
 
 #if defined(OS_ANDROID)
-    {"omnibox-on-device-head-suggestions",
-     flag_descriptions::kOmniboxOnDeviceHeadSuggestionsName,
-     flag_descriptions::kOmniboxOnDeviceHeadSuggestionsDescription, kOsAndroid,
-     FEATURE_VALUE_TYPE(omnibox::kOnDeviceHeadProvider)},
-
     {"omnibox-search-engine-logo",
      flag_descriptions::kOmniboxSearchEngineLogoName,
      flag_descriptions::kOmniboxSearchEngineLogoDescription, kOsAndroid,
@@ -2695,6 +2690,11 @@ const FeatureEntry kFeatureEntries[] = {
                                     "OmniboxSearchEngineLogo")},
 #endif  // defined(OS_ANDROID)
 
+    {"omnibox-on-device-head-suggestions",
+     flag_descriptions::kOmniboxOnDeviceHeadSuggestionsName,
+     flag_descriptions::kOmniboxOnDeviceHeadSuggestionsDescription, kOsAll,
+     FEATURE_VALUE_TYPE(omnibox::kOnDeviceHeadProvider)},
+
     {"omnibox-rich-entity-suggestions",
      flag_descriptions::kOmniboxRichEntitySuggestionsName,
      flag_descriptions::kOmniboxRichEntitySuggestionsDescription, kOsAll,