Reland fast tab closure behind a flag

chrome/common/chrome_switches.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/common/chrome_switches.h"
 
 #include "base/base_switches.h"
 #include "base/command_line.h"
 
 namespace switches {
@@ skipping 534 matching lines @@
     "enable-extension-activity-log-testing";
 
 // Enables or disables showing extensions in the action box.
 const char kExtensionsInActionBox[]         = "extensions-in-action-box";
 
 // Enables or disables running extensions on chrome:// URLs.
 // Extensions still need to explicitly request access to chrome:// URLs in the
 // manifest.
 const char kExtensionsOnChromeURLs[]        = "extensions-on-chrome-urls";
 
+// Enable the fast unload controller, which speeds up tab/window close by
+// running a tab's onunload js handler independently of the GUI -
+// crbug.com/142458 .
+const char kEnableFastUnload[]         = "enable-fast-unload";
+
 // By default, cookies are not allowed on file://. They are needed for testing,
 // for example page cycler and layout tests. See bug 1157243.
 const char kEnableFileCookies[]             = "enable-file-cookies";
 
 // Enables Google Now integration.
 const char kEnableGoogleNowIntegration[]    = "enable-google-now-integration";
 
 // Enable Instant extended API. On mobile, this merely enables query extraction,
 // not the rest of the instant-extended functionality.
 const char kEnableInstantExtendedAPI[]      = "enable-instant-extended-api";
@@ skipping 1036 matching lines @@
 
 // -----------------------------------------------------------------------------
 // DO NOT ADD YOUR CRAP TO THE BOTTOM OF THIS FILE.
 //
 // You were going to just dump your switches here, weren't you? Instead, please
 // put them in alphabetical order above, or in order inside the appropriate
 // ifdef at the bottom. The order should match the header.
 // -----------------------------------------------------------------------------
 
 }  // namespace switches