Add a comment about a leak/suppression.

chrome/browser/browser_main_posix.cc

Index: chrome/browser/browser_main_posix.cc
diff --git a/chrome/browser/browser_main_posix.cc b/chrome/browser/browser_main_posix.cc
index 1f90bdcc1030186f82940983b614f6f83dcd2c2b..c3e028d4cb7801de85f5a3586b9b6c79dd0098f1 100644
--- a/chrome/browser/browser_main_posix.cc
+++ b/chrome/browser/browser_main_posix.cc
@@ -209,6 +209,8 @@ void BrowserMainPartsPosix::PostMainMessageLoopStart() {
     g_shutdown_pipe_read_fd = pipefd[0];
     g_shutdown_pipe_write_fd = pipefd[1];
     const size_t kShutdownDetectorThreadStackSize = 4096;
+    // TODO(viettrungluu,willchan): crbug.com/29675 - This currently leaks, so
+    // if you change this, you'll probably need to change the suppression.
     if (!PlatformThread::CreateNonJoinable(
         kShutdownDetectorThreadStackSize,
         new ShutdownDetector(g_shutdown_pipe_read_fd))) {