In WinAura, also kill the Metro viewer process in AttemptExit().

chrome/browser/lifetime/application_lifetime.cc

Index: chrome/browser/lifetime/application_lifetime.cc
diff --git a/chrome/browser/lifetime/application_lifetime.cc b/chrome/browser/lifetime/application_lifetime.cc
index 605e548001aa18ca115c08c3505fb35604e741b8..7c1d53278bbb273e7bf35851661cd4a966271635 100644
--- a/chrome/browser/lifetime/application_lifetime.cc
+++ b/chrome/browser/lifetime/application_lifetime.cc
@@ -47,6 +47,10 @@
 #include "chromeos/dbus/update_engine_client.h"
 #endif
 
+#if defined(OS_WIN) && defined(USE_AURA)
+#include "base/win/windows_version.h"
+#endif
+
 namespace chrome {
 namespace {
 
@@ -102,6 +106,14 @@ void AttemptExitInternal() {
 #else
   // On most platforms, closing all windows causes the application to exit.
   CloseAllBrowsers();
+#if defined(OS_WIN) && defined(USE_AURA)
+  if (base::win::GetVersion() >= base::win::VERSION_WIN8) {
+    // On Windows 8, Ash might be active in Metro and won't go away even if all
+    // browsers are closed. The viewer process, whose host holds a reference to
+    // g_browser_process, needs to be killed.
+    g_browser_process->TerminateMetroViewerProcess();
+  }
+#endif  // defined(OS_WIN) && defined(USE_AURA)
 #endif
 }