Move implementation from header to source.

base/command_line.h

Index: base/command_line.h
diff --git a/base/command_line.h b/base/command_line.h
index b2b4185cd53797439f4e26c8fe96fa1bc3b25178..c68711af4905cf1a9551d570aa92b43b9e62f783 100644
--- a/base/command_line.h
+++ b/base/command_line.h
@@ -35,6 +35,7 @@ class CommandLine {
   // A constructor for CommandLines that are used only to carry arguments.
   enum ArgumentsOnly { ARGUMENTS_ONLY };
   explicit CommandLine(ArgumentsOnly args_only);
+  ~CommandLine();
 
 #if defined(OS_WIN)
   // The type of native command line arguments.
@@ -203,7 +204,7 @@ class CommandLine {
  private:
   friend class InProcessBrowserTest;
 
-  CommandLine() {}
+  CommandLine();
 
   // Used by InProcessBrowserTest.
   static CommandLine* ForCurrentProcessMutable() {