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

base/win/metro.h

 // 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.
 
 #ifndef BASE_WIN_METRO_H_
 #define BASE_WIN_METRO_H_
 #pragma once
 
 #include <windows.h>
 
@@ skipping 23 matching lines @@
   CLOSEDBYUSER,
   LASTEXECUTIONSTATE,
 };
 
 // Contains information about the currently displayed tab in metro mode.
 struct CurrentTabInfo {
   wchar_t* title;
   wchar_t* url;
 };
 
+// The types of exports in metro_driver.dll.
+typedef HRESULT (*ActivateApplicationFn)(const wchar_t*);
+
+// The names of the exports in metro_driver.dll.
+BASE_EXPORT extern const char kActivateApplication[];
+
 // Returns the handle to the metro dll loaded in the process. A NULL return
 // indicates that the metro dll was not loaded in the process.
 BASE_EXPORT HMODULE GetMetroModule();
 
 // Allocates and returns the destination string via the LocalAlloc API after
 // copying the src to it.
 BASE_EXPORT wchar_t* LocalAllocAndCopyString(const string16& src);
 
 }  // namespace win
 }  // namespace base
 
 #endif  // BASE_WIN_METRO_H_