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

chrome/browser/first_run/upgrade_util_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/first_run/upgrade_util.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/base_paths.h"
 #include "base/command_line.h"
 #include "base/environment.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/logging.h"
 #include "base/path_service.h"
+#include "base/process.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/common/chrome_constants.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/installer/util/browser_distribution.h"
 #include "chrome/installer/util/google_update_constants.h"
 #include "chrome/installer/util/install_util.h"
@@ skipping 25 matching lines @@
       DWORD exit_code;
       ::GetExitCodeProcess(handle, &exit_code);
       ::CloseHandle(handle);
       if (exit_code == installer::RENAME_SUCCESSFUL)
         return true;
     }
   }
   return false;
 }
 
+FilePath GetRelauncherPath(base::Environment* env,

[cpu_(ooo_6.6-7.5), 2012/06/29 21:32:39]

needs a better name, like GetMetroRelauncherPath

[grt (UTC plus 2), 2012/07/31 21:44:03]

Done.

+                           const FilePath& chrome_exe) {
+  std::string version_str;
+

[cpu_(ooo_6.6-7.5), 2012/06/29 21:32:39]

kill this empty line

[grt (UTC plus 2), 2012/07/31 21:44:03]

Done.

+  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 (env->GetVar(chrome::kChromeVersionEnvVar, &version_str))
+    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);
+
+  if (!base::win::IsMetroProcess()) {
+    env->UnSetVar(chrome::kChromeVersionEnvVar);
+    return base::LaunchProcess(command_line, base::LaunchOptions(), NULL);
+  }
+
+  // Pass this Chrome's handle and AppUserModelID to the relauncher.  The
+  // relauncher will wait for this Chrome to exit then reactivate it.
+  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(GetRelauncherPath(env.get(), chrome_exe));
+  relaunch_cmd.AppendSwitchNative(switches::kActivateApp,
+      ShellUtil::GetBrowserModelId(BrowserDistribution::GetDistribution(),
+                                   chrome_exe.value()));
+  relaunch_cmd.AppendSwitchNative(switches::kWaitForHandle,
+      base::PointerToString16(process_handle.Get()));
+
+  // Relaunch.
+  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;
+  }
+
+  // Ownership of the duplicated handle has been passed to the child process.
+  ignore_result(process_handle.Take());

[grt (UTC plus 2), 2012/07/31 21:44:03]

It's my understanding that both processes need to release their copy of
inherited handles independently, so I believe that this line of code actually
caused a leak rather than preventing a double-free.  Does this sound right to
you?

+  return true;
 }
 
 bool IsUpdatePendingRestart() {
   FilePath new_chrome_exe;
   if (!GetNewerChromeFile(&new_chrome_exe))
     return false;
   return file_util::PathExists(new_chrome_exe);
 }
 
 bool SwapNewChromeExeIfPresent() {
@@ skipping 71 matching lines @@
     return false;
   // At this point the chrome.exe has been swapped with the new one.
   if (!RelaunchChromeBrowser(command_line)) {
     // The re-launch fails. Feel free to panic now.
     NOTREACHED();
   }
   return true;
 }
 
 }  // namespace upgrade_util