Recommend base::test::ScopedCommandLine usage.

base/command_line.h

Index: base/command_line.h
diff --git a/base/command_line.h b/base/command_line.h
index 860d1c2c06be27d8784b64924294bd96538f5787..3d29f8fee7fbb8de9e8c1fb691515ddb8bdccbdd 100644
--- a/base/command_line.h
+++ b/base/command_line.h
@@ -33,15 +33,15 @@ class BASE_EXPORT CommandLine {
  public:
 #if defined(OS_WIN)
   // The native command line string type.
-  typedef base::string16 StringType;
+  using StringType = string16;
 #elif defined(OS_POSIX)
-  typedef std::string StringType;
+  using StringType = std::string;
 #endif
 
-  typedef StringType::value_type CharType;
-  typedef std::vector<StringType> StringVector;
-  typedef std::map<std::string, StringType> SwitchMap;
-  typedef std::map<base::StringPiece, const StringType*> StringPieceSwitchMap;
+  using CharType = StringType::value_type;
+  using StringVector = std::vector<StringType>;
+  using SwitchMap = std::map<std::string, StringType>;
+  using StringPieceSwitchMap = std::map<StringPiece, const StringType*>;
 
   // A constructor for CommandLines that only carry switches and arguments.
   enum NoProgram { NO_PROGRAM };
@@ -90,6 +90,7 @@ class BASE_EXPORT CommandLine {
   // you want to reset the base library to its initial state (for example, in an
   // outer library that needs to be able to terminate, and be re-initialized).
   // If Init is called only once, as in main(), Reset() is not necessary.
+  // Do not call this in tests. Use base::test::ScopedCommandLine instead.
   static void Reset();
 
   // Get the singleton CommandLine representing the current process's
@@ -101,7 +102,7 @@ class BASE_EXPORT CommandLine {
   static bool InitializedForCurrentProcess();
 
 #if defined(OS_WIN)
-  static CommandLine FromString(const base::string16& command_line);
+  static CommandLine FromString(const string16& command_line);
 #endif
 
   // Initialize from an argv vector.
@@ -159,15 +160,15 @@ class BASE_EXPORT CommandLine {
   // The second override provides an optimized version to avoid inlining codegen
   // at every callsite to find the length of the constant and construct a
   // StringPiece.
-  bool HasSwitch(const base::StringPiece& switch_string) const;
+  bool HasSwitch(const StringPiece& switch_string) const;

[Lei Zhang, 2016/07/14 10:24:22]

Shall we pass these by value while we are here?

[Mark Mentovai, 2016/07/14 14:24:02]

Lei Zhang (Slow Thursday) wrote:
How would that help?

[Lei Zhang, 2016/07/15 00:44:39]

base::StringPiece (and base::Time) says to prefer passing by value, but others
pass by ref for consistency. Not sure if you had a strong opinion on this.

   bool HasSwitch(const char switch_constant[]) const;
 
   // Returns the value associated with the given switch. If the switch has no
   // value or isn't present, this method returns the empty string.
   // Switch names must be lowercase.
-  std::string GetSwitchValueASCII(const base::StringPiece& switch_string) const;
-  FilePath GetSwitchValuePath(const base::StringPiece& switch_string) const;
-  StringType GetSwitchValueNative(const base::StringPiece& switch_string) const;
+  std::string GetSwitchValueASCII(const StringPiece& switch_string) const;
+  FilePath GetSwitchValuePath(const StringPiece& switch_string) const;
+  StringType GetSwitchValueNative(const StringPiece& switch_string) const;
 
   // Get a copy of all switches, along with their values.
   const SwitchMap& GetSwitches() const { return switches_; }
@@ -210,7 +211,7 @@ class BASE_EXPORT CommandLine {
 #if defined(OS_WIN)
   // Initialize by parsing the given command line string.
   // The program name is assumed to be the first item in the string.
-  void ParseFromString(const base::string16& command_line);
+  void ParseFromString(const string16& command_line);
 #endif
 
  private: