ProcessSingleton now uses base::win::MessageWindow to create a message-only window.

chrome/browser/chrome_process_finder_win.cc

Index: chrome/browser/chrome_process_finder_win.cc
diff --git a/chrome/browser/chrome_process_finder_win.cc b/chrome/browser/chrome_process_finder_win.cc
index c7a4985045c6f321a7e55d43d2a72f07c4b1ad85..1ca4be325eaff91d2c04bf904584ff34bea69df1 100644
--- a/chrome/browser/chrome_process_finder_win.cc
+++ b/chrome/browser/chrome_process_finder_win.cc
@@ -16,6 +16,7 @@
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/win/message_window.h"
 #include "base/win/metro.h"
 #include "base/win/scoped_handle.h"
 #include "base/win/win_util.h"
@@ -93,13 +94,12 @@ std::string EscapeQueryParamValue(const std::string& text, bool use_plus) {
 
 // END COPY from net/base/escape.cc
 
-}
+}  // namespace
 
 namespace chrome {
 
 HWND FindRunningChromeWindow(const base::FilePath& user_data_dir) {
-  return FindWindowEx(HWND_MESSAGE, NULL, chrome::kMessageWindowClass,
-                      user_data_dir.value().c_str());
+  return base::win::MessageWindow::FindWindow(user_data_dir.value());
 }
 
 NotifyChromeResult AttemptToNotifyRunningChrome(HWND remote_window) {