Relaunch Chrome in metro-mode with the help of a helper process.

chrome/browser/first_run/upgrade_util_win.cc

Index: chrome/browser/first_run/upgrade_util_win.cc
diff --git a/chrome/browser/first_run/upgrade_util_win.cc b/chrome/browser/first_run/upgrade_util_win.cc
index 834a9790a0fdde336dc60a0e5d1e08fd8ca1ca56..6569562f04492a754345800c38dce59b8f11c784 100644
--- a/chrome/browser/first_run/upgrade_util_win.cc
+++ b/chrome/browser/first_run/upgrade_util_win.cc
@@ -15,11 +15,13 @@
 #include "base/logging.h"
 #include "base/path_service.h"
 #include "base/process_util.h"
+#include "base/string_number_conversions.h"
 #include "base/string_util.h"
 #include "base/win/metro.h"
 #include "base/win/registry.h"
 #include "base/win/scoped_comptr.h"
 #include "chrome/browser/first_run/upgrade_util_win.h"
+#include "chrome/browser/shell_integration.h"
 #include "chrome/common/chrome_constants.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/installer/util/browser_distribution.h"
@@ -60,14 +62,70 @@ bool InvokeGoogleUpdateForRename() {
   return false;
 }
 
+FilePath GetMetroRelauncherPath(const FilePath& chrome_exe,
+                                const std::string version_str) {
+  FilePath path(chrome_exe.DirName());
+
+  // The relauncher is ordinarily in the version directory.  When running in a
+  // build tree however (where CHROME_VERSION is not set in the environment)
+  // look for it in Chrome's directory.
+  if (!version_str.empty())
+    path = path.AppendASCII(version_str);
+
+  return path.Append(installer::kDelegateExecuteExe);
+}
+
 }  // namespace
 
 namespace upgrade_util {
 
 bool RelaunchChromeBrowser(const CommandLine& command_line) {
   scoped_ptr<base::Environment> env(base::Environment::Create());
-  env->UnSetVar(chrome::kChromeVersionEnvVar);
-  return base::LaunchProcess(command_line, base::LaunchOptions(), NULL);
+  std::string version_str;
+
+  // Get the version variable and remove it from the environment.
+  if (env->GetVar(chrome::kChromeVersionEnvVar, &version_str))
+    env->UnSetVar(chrome::kChromeVersionEnvVar);
+  else
+    version_str.clear();
+
+  if (!base::win::IsMetroProcess())
+    return base::LaunchProcess(command_line, base::LaunchOptions(), NULL);
+
+  // Pass this Chrome's Start Menu shortcut path and handle to the relauncher.
+  // The relauncher will wait for this Chrome to exit then reactivate it by
+  // way of the Start Menu shortcut.
+  FilePath chrome_exe;
+  if (!PathService::Get(base::FILE_EXE, &chrome_exe)) {
+    NOTREACHED();
+    return false;
+  }
+
+  // Get a handle to this process that can be passed to the relauncher.
+  HANDLE current_process = GetCurrentProcess();
+  base::win::ScopedHandle process_handle;
+  if (!::DuplicateHandle(current_process, current_process, current_process,
+                         process_handle.Receive(), SYNCHRONIZE, TRUE, 0)) {
+    DPCHECK(false);
+    return false;
+  }
+
+  // Make the command line for the relauncher.
+  CommandLine relaunch_cmd(GetMetroRelauncherPath(chrome_exe, version_str));
+  relaunch_cmd.AppendSwitchPath(switches::kRelaunchShortcut,
+      ShellIntegration::GetStartMenuShortcut(chrome_exe));
+  relaunch_cmd.AppendSwitchNative(switches::kWaitForHandle,
+      base::UintToString16(reinterpret_cast<uint32>(process_handle.Get())));
+
+  base::LaunchOptions launch_options;
+  launch_options.inherit_handles = true;
+  if (!base::LaunchProcess(relaunch_cmd, launch_options, NULL)) {
+    DPLOG(ERROR) << "Failed to launch relauncher \""
+                 << relaunch_cmd.GetCommandLineString() << "\"";
+    return false;
+  }
+
+  return true;
 }
 
 bool IsUpdatePendingRestart() {