Allow callers of CommandLine::Init to know whether they were the first caller.

base/command_line.h

Index: base/command_line.h
diff --git a/base/command_line.h b/base/command_line.h
index a932a052144f96f53ecb4078cbe3861820d210c4..978ae03fbab6c6e6cc0e422f83d10aa9d82ae897 100644
--- a/base/command_line.h
+++ b/base/command_line.h
@@ -55,8 +55,10 @@ class BASE_EXPORT CommandLine {
   // Initialize the current process CommandLine singleton. On Windows, ignores
   // its arguments (we instead parse GetCommandLineW() directly) because we
   // don't trust the CRT's parsing of the command line, but it still must be
-  // called to set up the command line.
-  static void Init(int argc, const char* const* argv);
+  // called to set up the command line. Returns false if initialization has
+  // already occurred, and true otherwise. Only the caller receiving a 'true'
+  // return value should take responsibility for calling Reset.
+  static bool Init(int argc, const char* const* argv);
 
   // Destroys the current process CommandLine singleton. This is necessary if
   // you want to reset the base library to its initial state (for example, in an