Support Using ScopedFeatureList in BrowserTest

base/command_line.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 "base/command_line.h"
 
 #include <algorithm>
 #include <ostream>
 
 #include "base/files/file_path.h"
@@ skipping 347 matching lines @@
 
 void CommandLine::AppendSwitchASCII(const std::string& switch_string,
                                     const std::string& value_string) {
 #if defined(OS_WIN)
   AppendSwitchNative(switch_string, ASCIIToUTF16(value_string));
 #elif defined(OS_POSIX)
   AppendSwitchNative(switch_string, value_string);
 #endif
 }
 
+void CommandLine::RemoveSwitchASCIIForTesting(
+    const std::string& switch_string) {
+#if defined(OS_WIN)
+  const std::string switch_key = ToLowerASCII(switch_string);
+  StringType combined_switch_string(ASCIIToUTF16(switch_key));
+#elif defined(OS_POSIX)
+  const std::string& switch_key = switch_string;
+  StringType combined_switch_string(switch_key);
+#endif

[Ilya Sherman, 2017/06/07 21:32:36]

These few lines are duplicated from above.  Please factor out a small helper
function for this rather than copy/pasting them.

+  size_t prefix_length = GetSwitchPrefixLength(combined_switch_string);
+  switches_by_stringpiece_.erase(switch_key.substr(prefix_length));
+  switches_.erase(switch_string.substr(prefix_length));

[Ilya Sherman, 2017/06/07 21:32:36]

Does argv_ need to be updated as well?  (I am not familiar with the details of
the CommandLine implementation, so I'm just judging by the fact that it's set in
AppendSwitchNative().)

+}
+
 void CommandLine::CopySwitchesFrom(const CommandLine& source,
                                    const char* const switches[],
                                    size_t count) {
   for (size_t i = 0; i < count; ++i) {
     if (source.HasSwitch(switches[i]))
       AppendSwitchNative(switches[i], source.GetSwitchValueNative(switches[i]));
   }
 }
 
 CommandLine::StringVector CommandLine::GetArgs() const {
@@ skipping 111 matching lines @@
   return params;
 }
 
 void CommandLine::ResetStringPieces() {
   switches_by_stringpiece_.clear();
   for (const auto& entry : switches_)
     switches_by_stringpiece_[entry.first] = &(entry.second);
 }
 
 }  // namespace base