Fix comment for posix LaunchApp wrt PATH searching.

base/process_util.h

Index: base/process_util.h
diff --git a/base/process_util.h b/base/process_util.h
index 706cf5ffc9a0bf4a0db27fafab76923088d11038..f3e47fd1deca895060873c538e4876c061d052dd 100644
--- a/base/process_util.h
+++ b/base/process_util.h
@@ -135,8 +135,8 @@ bool LaunchApp(const std::wstring& cmdline,
 // As above, if wait is true, execute synchronously. The pid will be stored
 // in process_handle if that pointer is non-null.
 //
-// Note that the first argument in argv must point to the filename,
-// and must be fully specified.
+// Note that the first argument in argv must point to the executable filename.
+// If the filename is not fully specified, PATH will be searched.
 typedef std::vector<std::pair<int, int> > file_handle_mapping_vector;
 bool LaunchApp(const std::vector<std::string>& argv,
                const file_handle_mapping_vector& fds_to_remap,