Extract arguments reconstruction logic out of GetCommandLineString() into GetArgumentsString().

base/command_line.h

Index: base/command_line.h
diff --git a/base/command_line.h b/base/command_line.h
index 37cc71babb48228db59a3ff7f80ba425f31ef634..7d8627fa8417f33c77cc22c88e706ef821d78b50 100644
--- a/base/command_line.h
+++ b/base/command_line.h
@@ -79,9 +79,15 @@ class BASE_EXPORT CommandLine {
   void InitFromArgv(const StringVector& argv);
 
   // Constructs and returns the represented command line string.
-  // CAUTION! This should be avoided because quoting behavior is unclear.
+  // CAUTION! This should be avoided on POSIX because quoting behavior is
+  // unclear.
   StringType GetCommandLineString() const;
 
+  // Constructs and returns the represented arguments string.
+  // CAUTION! This should be avoided on POSIX because quoting behavior is
+  // unclear.
+  StringType GetArgumentsString() const;
+
   // Returns the original command line string as a vector of strings.
   const StringVector& argv() const { return argv_; }