base::CommandLine: Replace use of wstring with string16.

wstring is deprecated in Chromium. Since all the code in CommandLine
using wstring is Windows-only, string16 is equivalent.

This change is necessary to avoid a presubmit warning when touching the
CommandLine code.

BUG=416785

Review URL: https://codereview.chromium.org/602253006

Cr-Commit-Position: refs/heads/master@{#297608}


CrOS-Libchrome-Original-Commit: c9e499ed9ecf90352c57e85811869c70a9bce7cc
diff --git a/base/command_line.h b/base/command_line.h
index fd06e61..84bca28 100644
--- a/base/command_line.h
+++ b/base/command_line.h
@@ -21,6 +21,7 @@
 #include <vector>
 
 #include "base/base_export.h"
+#include "base/strings/string16.h"
 #include "build/build_config.h"
 
 namespace base {
@@ -31,7 +32,7 @@
  public:
 #if defined(OS_WIN)
   // The native command line string type.
-  typedef std::wstring StringType;
+  typedef base::string16 StringType;
 #elif defined(OS_POSIX)
   typedef std::string StringType;
 #endif
@@ -87,7 +88,7 @@
   static bool InitializedForCurrentProcess();
 
 #if defined(OS_WIN)
-  static CommandLine FromString(const std::wstring& command_line);
+  static CommandLine FromString(const base::string16& command_line);
 #endif
 
   // Initialize from an argv vector.
@@ -162,7 +163,7 @@
 #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 std::wstring& command_line);
+  void ParseFromString(const base::string16& command_line);
 #endif
 
  private: