Updated the comment explaining the behavior of --overscroll-history-navigation flag.

content/public/common/content_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 "content/public/common/content_switches.h"
 
 #include "base/command_line.h"
 
 namespace switches {
 
@@ skipping 576 matching lines @@
 
 // Don't send HTTP-Referer headers.
 const char kNoReferrers[]                   = "no-referrers";
 
 // Disables the sandbox for all process types that are normally sandboxed.
 const char kNoSandbox[]                     = "no-sandbox";
 
 // Number of worker threads used to rasterize content.
 const char kNumRasterThreads[]              = "num-raster-threads";
 
-// Enables or disables history navigation in response to horizontal overscroll.
-// Set the value to '1' to enable the feature, and set to '0' to disable.
-// Defaults to enabled.
+// Controls the behavior of history navigation in response to horizontal
+// overscroll.
+// Set the value to '0' to disable.
+// Set the value to '1' to enable the behavior where pages slide in and out in
+// response to the horizontal overscroll gesture and a screenshot of the target
+// page is shown.
+// Set the value to '2' to enable the simplified overscroll UI where a
+// navigation arrow slides in from the side of the screen in response to the
+// horizontal overscroll gesture.
+// Defaults to '1'.
 const char kOverscrollHistoryNavigation[] =
     "overscroll-history-navigation";
 
 // Specifies a command that should be used to launch the plugin process.  Useful
 // for running the plugin process through purify or quantify.  Ex:
 //   --plugin-launcher="path\to\purify /Run=yes"
 const char kPluginLauncher[]                = "plugin-launcher";
 
 // Tells the plugin process the path of the plugin to load
 const char kPluginPath[]                    = "plugin-path";
@@ skipping 305 matching lines @@
 // Enable the Win32K process mitigation policy for renderer processes which
 // prevents them from invoking user32 and gdi32 system calls which enter
 // the kernel. This is only supported on Windows 8 and beyond.
 const char kEnableWin32kRendererLockDown[]
     = "enable_win32k_renderer_lockdown";
 #endif
 
 // Don't dump stuff here, follow the same order as the header.
 
 }  // namespace switches