Reland fast tab closure behind a flag

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 <algorithm>
 #include <iterator>
 #include <map>
 #include <set>
@@ skipping 523 matching lines @@
     SINGLE_VALUE_TYPE(switches::kEnableExperimentalExtensionApis)
   },
   {
     "extensions-on-chrome-urls",
     IDS_FLAGS_EXTENSIONS_ON_CHROME_URLS_NAME,
     IDS_FLAGS_EXTENSIONS_ON_CHROME_URLS_DESCRIPTION,
     kOsAll,
     SINGLE_VALUE_TYPE(switches::kExtensionsOnChromeURLs)
   },
   {
+    "enable-fast-unload",
+    IDS_FLAGS_ENABLE_FAST_UNLOAD_NAME,
+    IDS_FLAGS_ENABLE_FAST_UNLOAD_DESCRIPTION,
+    kOsAll,
+    SINGLE_VALUE_TYPE(switches::kEnableFastUnload)
+  },
+  {
     "enable-adview",
     IDS_FLAGS_ENABLE_ADVIEW_NAME,
     IDS_FLAGS_ENABLE_ADVIEW_DESCRIPTION,
     kOsDesktop,
     SINGLE_VALUE_TYPE(switches::kEnableAdview)
   },
   {
     "enable-adview-src-attribute",
     IDS_FLAGS_ENABLE_ADVIEW_SRC_ATTRIBUTE_NAME,
     IDS_FLAGS_ENABLE_ADVIEW_SRC_ATTRIBUTE_DESCRIPTION,
@@ skipping 1524 matching lines @@
 }
 
 const Experiment* GetExperiments(size_t* count) {
   *count = num_experiments;
   return experiments;
 }
 
 }  // namespace testing
 
 }  // namespace about_flags