Add chrome://flags entry to enable the standalone content suggestions UI.

chrome/browser/about_flags.cc

 // Copyright (c) 2012 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/about_flags.h"
 
 #include <iterator>
 #include <map>
 #include <set>
 #include <utility>
@@ skipping 1896 matching lines @@
      IDS_FLAGS_ENABLE_NTP_BOOKMARK_SUGGESTIONS_DESCRIPTION, kOsAndroid,
      FEATURE_VALUE_TYPE(ntp_snippets::kBookmarkSuggestionsFeature)},
     {"enable-ntp-physical-web-page-suggestions",
      IDS_FLAGS_ENABLE_NTP_PHYSICAL_WEB_PAGE_SUGGESTIONS_NAME,
      IDS_FLAGS_ENABLE_NTP_PHYSICAL_WEB_PAGE_SUGGESTIONS_DESCRIPTION, kOsAndroid,
      FEATURE_VALUE_TYPE(ntp_snippets::kPhysicalWebPageSuggestionsFeature)},
     {"enable-ntp-foreign-sessions-suggestions",
      IDS_FLAGS_ENABLE_NTP_FOREIGN_SESSIONS_SUGGESTIONS_NAME,
      IDS_FLAGS_ENABLE_NTP_FOREIGN_SESSIONS_SUGGESTIONS_DESCRIPTION, kOsAndroid,
      FEATURE_VALUE_TYPE(ntp_snippets::kForeignSessionsSuggestionsFeature)},
+    {"ntp-standalone-suggestions-ui",
+     IDS_FLAGS_ENABLE_NTP_STANDALONE_SUGGESTIONS_UI_NAME,
+     IDS_FLAGS_ENABLE_NTP_STANDALONE_SUGGESTIONS_UI_DESCRIPTION, kOsAndroid,
+     FEATURE_VALUE_TYPE(chrome::android::kNTPSuggestionsStandaloneUIFeature)},
 #endif  // OS_ANDROID
 #if BUILDFLAG(ENABLE_WEBRTC) && BUILDFLAG(RTC_USE_H264) && \
     !defined(MEDIA_DISABLE_FFMPEG)
     {"enable-webrtc-h264-with-openh264-ffmpeg",
      IDS_FLAGS_WEBRTC_H264_WITH_OPENH264_FFMPEG_NAME,
      IDS_FLAGS_WEBRTC_H264_WITH_OPENH264_FFMPEG_DESCRIPTION, kOsDesktop,
      FEATURE_VALUE_TYPE(content::kWebRtcH264WithOpenH264FFmpeg)},
 #endif  // ENABLE_WEBRTC && BUILDFLAG(RTC_USE_H264) && !MEDIA_DISABLE_FFMPEG
 #if defined(OS_ANDROID)
     {"offline-pages-ntp", IDS_FLAGS_NTP_OFFLINE_PAGES_NAME,
@@ skipping 455 matching lines @@
 const base::HistogramBase::Sample kBadSwitchFormatHistogramId = 0;
 
 const FeatureEntry* GetFeatureEntries(size_t* count) {
   *count = arraysize(kFeatureEntries);
   return kFeatureEntries;
 }
 
 }  // namespace testing
 
 }  // namespace about_flags