Autoplay: add document user activation flag in chrome://flags

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 739 matching lines @@
      switches::kAutoplayPolicy,
      switches::autoplay::kNoUserGestureRequiredPolicy},
 #if defined(OS_ANDROID)
     {flag_descriptions::kAutoplayPolicyUserGestureRequired,
      switches::kAutoplayPolicy, switches::autoplay::kUserGestureRequiredPolicy},
 #else
     {flag_descriptions::kAutoplayPolicyUserGestureRequiredForCrossOrigin,
      switches::kAutoplayPolicy,
      switches::autoplay::kUserGestureRequiredForCrossOriginPolicy},
 #endif
+    {flag_descriptions::kAutoplayPolicyDocumentUserActivation,
+     switches::kAutoplayPolicy,
+     switches::autoplay::kDocumentUserActivationRequiredPolicy},
 };
 
 const FeatureEntry::Choice kForceEffectiveConnectionTypeChoices[] = {
     {flags_ui::kGenericExperimentChoiceDefault, "", ""},
     {flag_descriptions::kEffectiveConnectionTypeUnknownDescription,
      switches::kForceEffectiveConnectionType,
      net::kEffectiveConnectionTypeUnknown},
     {flag_descriptions::kEffectiveConnectionTypeOfflineDescription,
      switches::kForceEffectiveConnectionType,
      net::kEffectiveConnectionTypeOffline},
@@ skipping 2513 matching lines @@
 const base::HistogramBase::Sample kBadSwitchFormatHistogramId = 0;
 
 const FeatureEntry* GetFeatureEntries(size_t* count) {
   *count = arraysize(kFeatureEntries);
   return kFeatureEntries;
 }
 
 }  // namespace testing
 
 }  // namespace about_flags