Support Using ScopedFeatureList in BrowserTest

base/command_line.h

 // 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.
 
 // This class works with command lines: building and parsing.
 // Arguments with prefixes ('--', '-', and on Windows, '/') are switches.
 // Switches will precede all other arguments without switch prefixes.
 // Switches can optionally have values, delimited by '=', e.g., "-switch=value".
 // An argument of "--" will terminate switch parsing during initialization,
 // interpreting subsequent tokens as non-switch arguments, regardless of prefix.
@@ skipping 164 matching lines @@
 
   // Append a switch [with optional value] to the command line.
   // Note: Switches will precede arguments regardless of appending order.
   void AppendSwitch(const std::string& switch_string);
   void AppendSwitchPath(const std::string& switch_string,
                         const FilePath& path);
   void AppendSwitchNative(const std::string& switch_string,
                           const StringType& value);
   void AppendSwitchASCII(const std::string& switch_string,
                          const std::string& value);
+  void ReplaceSwitchASCIIForTesting(const std::string& switch_string,
+                                    const std::string& value);

[Ilya Sherman, 2017/05/25 22:48:11]

I happened to find this code [1] in a code search.  It looks like it's trying to
do approximately the same thing you're doing.  Can we unify the code paths?

[1]
https://cs.chromium.org/chromium/src/android_webview/browser/command_line_hel...

[chaopeng, 2017/05/26 00:57:41]

CommandLineHelper try to feature only if feature not in enable or disable list.
ScopedFeatureList want to override feature. But I want to change
CommandLineHelper to call ReplaceSwitchASCII.

 
   // Copy a set of switches (and any values) from another command line.
   // Commonly used when launching a subprocess.
   void CopySwitchesFrom(const CommandLine& source,
                         const char* const switches[],
                         size_t count);
 
   // Get the remaining arguments to the command.
   StringVector GetArgs() const;
 
@@ skipping 55 matching lines @@
   // Used for allocation-free lookups.
   StringPieceSwitchMap switches_by_stringpiece_;
 
   // The index after the program and switches, any arguments start here.
   size_t begin_args_;
 };
 
 }  // namespace base
 
 #endif  // BASE_COMMAND_LINE_H_