Support Using ScopedFeatureList in BrowserTest

base/command_line.cc

Index: base/command_line.cc
diff --git a/base/command_line.cc b/base/command_line.cc
index 873da813483651bc9e74b0510e17fa925225b5bd..806e40d8e62be36ad6cf3f1747cb3258bc8f547d 100644
--- a/base/command_line.cc
+++ b/base/command_line.cc
@@ -365,6 +365,22 @@ void CommandLine::AppendSwitchASCII(const std::string& switch_string,
 #endif
 }
 
+void CommandLine::ReplaceSwitchASCIIForTesting(const std::string& switch_string,
+                                               const std::string& value) {
+#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
+  size_t prefix_length = GetSwitchPrefixLength(combined_switch_string);
+  switches_by_stringpiece_.erase(switch_key.substr(prefix_length));
+  switches_.erase(switch_string.substr(prefix_length));
+
+  AppendSwitchASCII(switch_string, value);
+}
+
 void CommandLine::CopySwitchesFrom(const CommandLine& source,
                                    const char* const switches[],
                                    size_t count) {