Change about flag for doc.write to a tri-state so it can be disabled.

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 1657 matching lines @@
      IDS_FLAGS_BACKGROUND_LOADER_FOR_DOWNLOADS_NAME,
      IDS_FLAGS_BACKGROUND_LOADER_FOR_DOWNLOADS_DESCRIPTION, kOsAndroid,
      FEATURE_VALUE_TYPE(offline_pages::kBackgroundLoaderForDownloadsFeature)},
 #endif  // OS_ANDROID
     {"disallow-doc-written-script-loads",
      IDS_FLAGS_DISALLOW_DOC_WRITTEN_SCRIPTS_UI_NAME,
      IDS_FLAGS_DISALLOW_DOC_WRITTEN_SCRIPTS_UI_DESCRIPTION, kOsAll,
      // NOTE: if we want to add additional experiment entries for other
      // features controlled by kBlinkSettings, we'll need to add logic to
      // merge the flag values.
-     SINGLE_VALUE_TYPE_AND_VALUE(
+     ENABLE_DISABLE_VALUE_TYPE_AND_VALUE(
          switches::kBlinkSettings,
-         "disallowFetchForDocWrittenScriptsInMainFrame=true")},
+         "disallowFetchForDocWrittenScriptsInMainFrame=true",
+         switches::kBlinkSettings,
+         "disallowFetchForDocWrittenScriptsInMainFrame=false")},
 #if defined(OS_ANDROID)
     {"enable-ntp-popular-sites", IDS_FLAGS_NTP_POPULAR_SITES_NAME,
      IDS_FLAGS_NTP_POPULAR_SITES_DESCRIPTION, kOsAndroid,
      ENABLE_DISABLE_VALUE_TYPE(ntp_tiles::switches::kEnableNTPPopularSites,
                                ntp_tiles::switches::kDisableNTPPopularSites)},
     {"ntp-switch-to-existing-tab", IDS_FLAGS_NTP_SWITCH_TO_EXISTING_TAB_NAME,
      IDS_FLAGS_NTP_SWITCH_TO_EXISTING_TAB_DESCRIPTION, kOsAndroid,
      MULTI_VALUE_TYPE(kNtpSwitchToExistingTabChoices)},
     {"use-android-midi-api", IDS_FLAGS_USE_ANDROID_MIDI_API_NAME,
      IDS_FLAGS_USE_ANDROID_MIDI_API_DESCRIPTION, kOsAndroid,
@@ skipping 572 matching lines @@
 const base::HistogramBase::Sample kBadSwitchFormatHistogramId = 0;
 
 const FeatureEntry* GetFeatureEntries(size_t* count) {
   *count = arraysize(kFeatureEntries);
   return kFeatureEntries;
 }
 
 }  // namespace testing
 
 }  // namespace about_flags