Ensure that Metro chrome in ASH is able to connect to an existing desktop chrome AURA process.

chrome/browser/browser_process_impl_win.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+#include "chrome/browser/browser_process_impl.h"
+
+#include "base/command_line.h"
+#include "chrome/common/chrome_switches.h"
+
+#if defined(USE_AURA)
+#include "chrome/browser/metro_viewer/metro_viewer_process_host_win.h"
+#endif
+
+void BrowserProcessImpl::PlatformSpecificCommandLineProcessing(
+    const CommandLine& command_line) {
+#if defined(USE_AURA)
+  PerformInitForWindowsAura(command_line);
+#endif
+}
+
+#if defined(USE_AURA)
+void BrowserProcessImpl::PerformInitForWindowsAura(
+    const CommandLine& command_line) {
+  if (command_line.HasSwitch(switches::kViewerConnection)) {
+    // Tell the metro viewer process host to connect to the given IPC channel.
+    metro_viewer_process_host_.reset(
+        new MetroViewerProcessHost(
+            command_line.GetSwitchValueASCII(switches::kViewerConnection)));
+  }
+}
+#endif