Add ShellIntegration::ActivateMetroChrome, which launches Chrome in metro-mode on Windows 8.

base/win/metro.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 "base/win/metro.h"
 
 #include "base/string_util.h"
 
 namespace base {
 namespace win {
 
+const char kActivateApplication[] = "ActivateApplication";
+
 HMODULE GetMetroModule() {
   return GetModuleHandleA("metro_driver.dll");
 }
 
 wchar_t* LocalAllocAndCopyString(const string16& src) {
   size_t dest_size = (src.length() + 1) * sizeof(wchar_t);
   wchar_t* dest = reinterpret_cast<wchar_t*>(LocalAlloc(LPTR, dest_size));
   base::wcslcpy(dest, src.c_str(), dest_size);
   return dest;
 }
 
 }  // namespace win
 }  // namespace base
-