Add comments and fix a potential leak in LaunchProcess.

base/process_util_win.cc

Index: base/process_util_win.cc
diff --git a/base/process_util_win.cc b/base/process_util_win.cc
index d640d683e3a5b805f7d2fbedf573a35a3bcfb8b1..ab60ce85bf047b83f484376cd00dacd52e417664 100644
--- a/base/process_util_win.cc
+++ b/base/process_util_win.cc
@@ -349,6 +349,8 @@ bool LaunchProcess(const string16& cmdline,
                                       process_info.hProcess)) {
       DLOG(ERROR) << "Could not AssignProcessToObject.";
       KillProcess(process_info.hProcess, kProcessKilledExitCode, true);
+      CloseHandle(process_info.hProcess);
+      CloseHandle(process_info.hThread);
       return false;
     }