[Chromoting] Don't use a job object to control the me2me host process on Windows XP.

remoting/host/win/wts_session_process_launcher.cc

Index: remoting/host/win/wts_session_process_launcher.cc
diff --git a/remoting/host/win/wts_session_process_launcher.cc b/remoting/host/win/wts_session_process_launcher.cc
index d659f156be51f2a91e7d86242f0edb463f28fa41..ee46c13731a1c93603fcc860d7baad31d89e739e 100644
--- a/remoting/host/win/wts_session_process_launcher.cc
+++ b/remoting/host/win/wts_session_process_launcher.cc
@@ -24,6 +24,7 @@
 #include "base/stringprintf.h"
 #include "base/utf_string_conversions.h"
 #include "base/win/scoped_handle.h"
+#include "base/win/windows_version.h"
 #include "ipc/ipc_channel_proxy.h"
 #include "ipc/ipc_message.h"
 #include "ipc/ipc_message_macros.h"
@@ -66,19 +67,233 @@ const char kDaemonIpcSecurityDescriptor[] = "O:SYG:SYD:(A;;GA;;;SY)";
 
 namespace remoting {
 
-WtsSessionProcessLauncher::WtsSessionProcessLauncher(
-    const base::Closure& stopped_callback,
-    WtsConsoleMonitor* monitor,
-    scoped_refptr<base::SingleThreadTaskRunner> main_message_loop,
-    scoped_refptr<base::SingleThreadTaskRunner> ipc_message_loop)
-    : Stoppable(main_message_loop, stopped_callback),
-      attached_(false),
-      main_message_loop_(main_message_loop),
-      ipc_message_loop_(ipc_message_loop),
-      monitor_(monitor),
-      job_state_(kJobUninitialized) {
-  monitor_->AddWtsConsoleObserver(this);
+class WtsProcessLauncherImpl
+    : public base::RefCountedThreadSafe<WtsProcessLauncherImpl>,
+      public WorkerProcessLauncher::Delegate {
+ public:
+  // Returns the exit code of the worker process.
+  virtual DWORD GetExitCode() = 0;
+
+  // Sets the token to be used to launch the worker process.
+  virtual bool SetSessionToken(HANDLE session_token) = 0;
+
+  // Stops the object asynchronously.
+  virtual void Stop() = 0;
+
+ protected:
+  friend class base::RefCountedThreadSafe<WtsProcessLauncherImpl>;
+  virtual ~WtsProcessLauncherImpl();
+};
+
+namespace {
+
+// Implements |WorkerProcessLauncher::Delegate| that starts the host process

[Wez, 2012/09/14 23:36:18]

nit: host process -> specified process?

[alexeypa (please no reviews), 2012/09/18 16:58:06]

Done.

+// in a different session via CreateProcessAsUser and uses the returned process
+// handle to control it.

[Wez, 2012/09/14 23:36:18]

nit: ... to monitor and close it. ?

[alexeypa (please no reviews), 2012/09/18 16:58:06]

Done.

+class SingleProcessLauncher : public WtsProcessLauncherImpl {
+ public:
+  SingleProcessLauncher(
+      const FilePath& binary,

[Wez, 2012/09/14 23:36:18]

nit: binary_path

[alexeypa (please no reviews), 2012/09/18 16:58:06]

Done.

+      scoped_refptr<base::SingleThreadTaskRunner> main_task_runner);
+
+  // WorkerProcessLauncher::Delegate implementation.
+  virtual bool DoLaunchProcess(
+      const std::string& channel_name,
+      base::win::ScopedHandle* process_exit_event_out) OVERRIDE;
+  virtual void DoKillProcess(DWORD exit_code) OVERRIDE;
+
+  // WtsProcessLauncherImpl implementation.
+  virtual DWORD GetExitCode() OVERRIDE;
+  virtual bool SetSessionToken(HANDLE session_token) OVERRIDE;
+  virtual void Stop() OVERRIDE;
+
+ private:
+  FilePath binary_;
+
+  // The main service message loop.
+  scoped_refptr<base::SingleThreadTaskRunner> main_task_runner_;
+
+  // A waiting handle that becomes signalled once all process associated with

[Wez, 2012/09/14 23:36:18]

nit: Handle that becomes ... once the process has terminated.

[alexeypa (please no reviews), 2012/09/18 16:58:06]

Done.

+  // the job have been terminated.
+  base::win::ScopedHandle process_exit_event_;
+
+  // The token to be used to launch a process in a different session.
+  base::win::ScopedHandle session_token_;
+
+  base::win::ScopedHandle worker_process_;
+
+  DISALLOW_COPY_AND_ASSIGN(SingleProcessLauncher);
+};
+
+// Implements |WorkerProcessLauncher::Delegate| that starts the host process
+// in a different session and uses job object to control it. This object

[Wez, 2012/09/14 23:36:18]

nit: You mention it uses [a] job object, and then start the next sentence with
"This object"; which I think you mean InJobLauncher rather than the job object?

[alexeypa (please no reviews), 2012/09/18 16:58:06]

Done.

+// utilizes a helper process to bypass limitations of ShellExecute() which
+// cannot spawn processes across the session boundary. ShellExecute() in its
+// turn is needed to start a binary specifying uiAccess='true' in its manifest.
+class InJobLauncher : public WtsProcessLauncherImpl,

[Wez, 2012/09/14 23:36:18]

nit: ShellExecuteLauncher?

Then you can describe this as a Delegate that launches the specified process via
ShellExecute() and document the use of helper process and job objects in
comments on the class members/method implementations.

[alexeypa (please no reviews), 2012/09/18 16:58:06]

Thinking about what this class is actually doing, I called it
ElevatedProcessLauncher.

+                      public base::MessagePumpForIO::IOHandler {
+ public:
+  InJobLauncher(
+      const FilePath& binary,
+      scoped_refptr<base::SingleThreadTaskRunner> main_task_runner,
+      scoped_refptr<base::SingleThreadTaskRunner> ipc_task_runner);
+
+  // base::MessagePumpForIO::IOHandler implementation.
+  virtual void OnIOCompleted(base::MessagePumpForIO::IOContext* context,
+                             DWORD bytes_transferred,
+                             DWORD error) OVERRIDE;
+
+  // WorkerProcessLauncher::Delegate implementation.
+  virtual bool DoLaunchProcess(
+      const std::string& channel_name,
+      base::win::ScopedHandle* process_exit_event_out) OVERRIDE;
+  virtual void DoKillProcess(DWORD exit_code) OVERRIDE;
+
+  // WtsProcessLauncherImpl implementation.
+  virtual DWORD GetExitCode() OVERRIDE;
+  virtual bool SetSessionToken(HANDLE session_token) OVERRIDE;
+  virtual void Stop() OVERRIDE;
+
+ private:
+  // Drains the completion port queue to make sure that all job object
+  // notifications has been received.

[Wez, 2012/09/14 23:36:18]

typo: has -> have

[alexeypa (please no reviews), 2012/09/18 16:58:06]

Done.

+  void DrainJobNotifications();
+
+  // Notifies that the completion port queue has been drained.
+  void DrainJobNotificationsCompleted();

[Wez, 2012/09/14 23:36:18]

Does this method trigger a notification, or is it called when a notification is
received? The name suggests the latter, in which case start the comment
"Notified when..."?

[alexeypa (please no reviews), 2012/09/18 16:58:06]

Done.

+
+  // Creates and initializes the job object that will sandbox the launched child
+  // processes.
+  void InitializeJob();
+
+  // Notifies that the job object initialization is complete.

[Wez, 2012/09/14 23:36:18]

nit: See above re "Notified when..."

[alexeypa (please no reviews), 2012/09/18 16:58:06]

Done.

+  void InitializeJobCompleted(scoped_ptr<base::win::ScopedHandle> job);
+
+  void OnJobNotification(DWORD message, DWORD pid);

[Wez, 2012/09/14 23:36:18]

nit: What's this for?

[alexeypa (please no reviews), 2012/09/18 16:58:06]

Done.

+
+  FilePath binary_;
+
+  // The main service message loop.

[Wez, 2012/09/14 23:36:18]

Can you re-describe this in terms of what this class uses the loop for?

[alexeypa (please no reviews), 2012/09/18 16:58:06]

Done.

+  scoped_refptr<base::SingleThreadTaskRunner> main_task_runner_;
+
+  // Message loop used by the IPC channel.
+  scoped_refptr<base::SingleThreadTaskRunner> ipc_task_runner_;
+
+  // The job object used to control the lifetime of child processes.
+  base::win::ScopedHandle job_;
+
+  // A waiting handle that becomes signalled once all process associated with
+  // the job have been terminated.
+  base::win::ScopedHandle process_exit_event_;
+
+  // The token to be used to launch a process in a different session.
+  base::win::ScopedHandle session_token_;
+
+  base::win::ScopedHandle worker_process_;

[Wez, 2012/09/14 23:36:18]

nit: Handle to the worker process, if launched?

[alexeypa (please no reviews), 2012/09/18 16:58:06]

Done.

+
+  DISALLOW_COPY_AND_ASSIGN(InJobLauncher);
+};
+
+SingleProcessLauncher::SingleProcessLauncher(
+    const FilePath& binary,
+    scoped_refptr<base::SingleThreadTaskRunner> main_task_runner)
+    : binary_(binary),
+      main_task_runner_(main_task_runner) {
+}
+
+bool SingleProcessLauncher::DoLaunchProcess(
+    const std::string& channel_name,
+    base::win::ScopedHandle* process_exit_event_out) {
+  DCHECK(main_task_runner_->BelongsToCurrentThread());
+
+  // Create the host process command line passing the name of the IPC channel

[Wez, 2012/09/14 23:36:18]

nit: host process command line -> command line?

[alexeypa (please no reviews), 2012/09/18 16:58:06]

Done.

+  // to use and copying known switches from the service's command line.

[Wez, 2012/09/14 23:36:18]

nit: service's -> caller's?

[alexeypa (please no reviews), 2012/09/18 16:58:06]

Done.

+  CommandLine command_line(binary_);
+  command_line.AppendSwitchNative(kDaemonIpcSwitchName,
+                                  UTF8ToWide(channel_name));
+  command_line.CopySwitchesFrom(*CommandLine::ForCurrentProcess(),
+                                kCopiedSwitchNames,
+                                _countof(kCopiedSwitchNames));
+
+  // Try to launch the process and attach an object watcher to the returned
+  // handle so that we get notified when the process terminates.
+  base::win::ScopedHandle worker_thread;
+  worker_process_.Close();
+  if (!LaunchProcessWithToken(binary_,
+                              command_line.GetCommandLineString(),
+                              session_token_,
+                              0,
+                              &worker_process_,
+                              &worker_thread)) {
+    return false;
+  }
+
+  ScopedHandle process_exit_event;
+  if (!DuplicateHandle(GetCurrentProcess(),
+                       worker_process_,
+                       GetCurrentProcess(),
+                       process_exit_event.Receive(),
+                       SYNCHRONIZE,
+                       FALSE,
+                       0)) {
+    LOG_GETLASTERROR(ERROR) << "Failed to duplicate a handle";
+    DoKillProcess(CONTROL_C_EXIT);
+    return false;
+  }
+
+  *process_exit_event_out = process_exit_event.Pass();
+  return true;
+}
+
+void SingleProcessLauncher::DoKillProcess(DWORD exit_code) {
+  DCHECK(main_task_runner_->BelongsToCurrentThread());
+
+  if (worker_process_.IsValid()) {
+    TerminateProcess(worker_process_, exit_code);
+  }
+}
+
+DWORD SingleProcessLauncher::GetExitCode() {
+  DWORD exit_code = CONTROL_C_EXIT;
+  if (worker_process_.IsValid()) {
+    if (!::GetExitCodeProcess(worker_process_, &exit_code)) {
+      LOG_GETLASTERROR(INFO)
+          << "Failed to query the exit code of the worker process";
+      exit_code = CONTROL_C_EXIT;
+    }
+
+    worker_process_.Close();
+  }
+
+  return exit_code;
+}
+
+bool SingleProcessLauncher::SetSessionToken(HANDLE session_token) {

[Wez, 2012/09/14 23:36:18]

nit: Rename this ResetUserToken() and have it take ownership of a supplied
ScopedHandle& to save duplicating Duplicate'ing code?

[alexeypa (please no reviews), 2012/09/18 16:58:06]

Done.

+  session_token_.Close();
+  if (!DuplicateHandle(GetCurrentProcess(),
+                       session_token,
+                       GetCurrentProcess(),
+                       session_token_.Receive(),
+                       0,
+                       FALSE,
+                       DUPLICATE_SAME_ACCESS)) {
+    LOG_GETLASTERROR(ERROR) << "Failed to duplicate a handle";
+    return false;
+  }
+
+  return true;
+}
 
+void SingleProcessLauncher::Stop() {
+}
+
+InJobLauncher::InJobLauncher(
+    const FilePath& binary,
+    scoped_refptr<base::SingleThreadTaskRunner> main_task_runner,
+    scoped_refptr<base::SingleThreadTaskRunner> ipc_task_runner)
+    : binary_(binary),
+      main_task_runner_(main_task_runner),
+      ipc_task_runner_(ipc_task_runner) {
   process_exit_event_.Set(CreateEvent(NULL, TRUE, FALSE, NULL));
   CHECK(process_exit_event_.IsValid());
 
@@ -86,60 +301,45 @@ WtsSessionProcessLauncher::WtsSessionProcessLauncher(
   // port represented by |ipc_message_loop|. The registration has to be done on
   // the I/O thread because MessageLoopForIO::RegisterJobObject() can only be
   // called via MessageLoopForIO::current().
-  ipc_message_loop_->PostTask(FROM_HERE, base::Bind(
-      &WtsSessionProcessLauncher::InitializeJob,
-      base::Unretained(this)));
+  ipc_task_runner_->PostTask(FROM_HERE,
+                             base::Bind(&InJobLauncher::InitializeJob, this));
 }
 
-WtsSessionProcessLauncher::~WtsSessionProcessLauncher() {
-  // Make sure that the object is completely stopped. The same check exists
-  // in Stoppable::~Stoppable() but this one helps us to fail early and
-  // predictably.
-  CHECK_EQ(stoppable_state(), Stoppable::kStopped);
-
-  monitor_->RemoveWtsConsoleObserver(this);
-
-  CHECK(!attached_);
-  CHECK(!timer_.IsRunning());
-}
-
-void WtsSessionProcessLauncher::OnIOCompleted(
+void InJobLauncher::OnIOCompleted(
     base::MessagePumpForIO::IOContext* context,
     DWORD bytes_transferred,
     DWORD error) {
-  DCHECK(ipc_message_loop_->BelongsToCurrentThread());
+  DCHECK(ipc_task_runner_->BelongsToCurrentThread());
 
   // |bytes_transferred| is used in job object notifications to supply
   // the message ID; |context| carries process ID.
-  main_message_loop_->PostTask(FROM_HERE, base::Bind(
-      &WtsSessionProcessLauncher::OnJobNotification,
-      base::Unretained(this), bytes_transferred,
+  main_task_runner_->PostTask(FROM_HERE, base::Bind(
+      &InJobLauncher::OnJobNotification, this, bytes_transferred,
       reinterpret_cast<DWORD>(context)));
 }
 
-bool WtsSessionProcessLauncher::DoLaunchProcess(
+bool InJobLauncher::DoLaunchProcess(
     const std::string& channel_name,
-    ScopedHandle* process_exit_event_out) {
-  DCHECK(main_message_loop_->BelongsToCurrentThread());
+    base::win::ScopedHandle* process_exit_event_out) {
+  DCHECK(main_task_runner_->BelongsToCurrentThread());
 
   // The job object is not ready. Retry starting the host process later.
   if (!job_.IsValid()) {
     return false;
   }
 
-  // Construct the host binary name.
+  // Construct the helper binary binary name.
   FilePath dir_path;
   if (!PathService::Get(base::DIR_EXE, &dir_path)) {
     LOG(ERROR) << "Failed to get the executable file name.";
     return false;
   }
-  FilePath host_binary = dir_path.Append(kMe2meHostBinaryName);
   FilePath service_binary = dir_path.Append(kMe2meServiceBinaryName);
 
   // Create the host process command line passing the name of the IPC channel
   // to use and copying known switches from the service's command line.
   CommandLine command_line(service_binary);
-  command_line.AppendSwitchPath(kElevateSwitchName, host_binary);
+  command_line.AppendSwitchPath(kElevateSwitchName, binary_);
   command_line.AppendSwitchNative(kDaemonIpcSwitchName,
                                   UTF8ToWide(channel_name));
   command_line.CopySwitchesFrom(*CommandLine::ForCurrentProcess(),
@@ -190,110 +390,76 @@ bool WtsSessionProcessLauncher::DoLaunchProcess(
   return true;
 }
 
-void WtsSessionProcessLauncher::DoKillProcess(DWORD exit_code) {
-  DCHECK(main_message_loop_->BelongsToCurrentThread());
+void InJobLauncher::DoKillProcess(DWORD exit_code) {
+  DCHECK(main_task_runner_->BelongsToCurrentThread());
 
   if (job_.IsValid()) {
     TerminateJobObject(job_, exit_code);
   }
 }
 
-void WtsSessionProcessLauncher::OnChannelConnected() {
-  DCHECK(main_message_loop_->BelongsToCurrentThread());
-}
-
-bool WtsSessionProcessLauncher::OnMessageReceived(const IPC::Message& message) {
-  DCHECK(main_message_loop_->BelongsToCurrentThread());
-
-  return false;
-}
-
-void WtsSessionProcessLauncher::OnSessionAttached(uint32 session_id) {
-  DCHECK(main_message_loop_->BelongsToCurrentThread());
+DWORD InJobLauncher::GetExitCode() {
+  DWORD exit_code = CONTROL_C_EXIT;
+  if (worker_process_.IsValid()) {
+    if (!::GetExitCodeProcess(worker_process_, &exit_code)) {
+      LOG_GETLASTERROR(INFO)
+          << "Failed to query the exit code of the worker process";
+      exit_code = CONTROL_C_EXIT;
+    }
 
-  if (stoppable_state() != Stoppable::kRunning) {
-    return;
+    worker_process_.Close();
   }
 
-  DCHECK(!attached_);
-  DCHECK(!timer_.IsRunning());
-
-  attached_ = true;
-
-  // Create a session token for the launched process.
-  if (!CreateSessionToken(session_id, &session_token_))
-    return;
-
-  // Now try to launch the host.
-  LaunchProcess();
+  return exit_code;
 }
 
-void WtsSessionProcessLauncher::OnSessionDetached() {
-  DCHECK(main_message_loop_->BelongsToCurrentThread());
-  DCHECK(attached_);
-
-  attached_ = false;
-  launch_backoff_ = base::TimeDelta();
+bool InJobLauncher::SetSessionToken(HANDLE session_token) {
   session_token_.Close();
-  timer_.Stop();
-
-  if (launcher_.get() != NULL) {
-    launcher_->Stop();
-  }
-}
-
-void WtsSessionProcessLauncher::DoStop() {
-  DCHECK(main_message_loop_->BelongsToCurrentThread());
-
-  if (attached_) {
-    OnSessionDetached();
+  if (!DuplicateHandle(GetCurrentProcess(),
+                       session_token,
+                       GetCurrentProcess(),
+                       session_token_.Receive(),
+                       0,
+                       FALSE,
+                       DUPLICATE_SAME_ACCESS)) {
+    LOG_GETLASTERROR(ERROR) << "Failed to duplicate a handle";
+    return false;
   }
 
-  job_.Close();
+  return true;
+}
 
+void InJobLauncher::Stop() {
   // Drain the completion queue to make sure all job object notification have
   // been received.
-  if (job_state_ == kJobRunning) {
-    job_state_ = kJobStopping;
-    ipc_message_loop_->PostTask(FROM_HERE, base::Bind(
-        &WtsSessionProcessLauncher::DrainJobNotifications,
-        base::Unretained(this)));
-  }
-
-  // Don't complete shutdown if |launcher_| is not completely stopped.
-  if (launcher_.get() != NULL) {
-    return;
-  }
-
-  // Don't complete shutdown if the completion queue hasn't been drained.
-  if (job_state_ != kJobUninitialized && job_state_ != kJobStopped) {
-    return;
-  }
-
-  CompleteStopping();
+  DrainJobNotificationsCompleted();
 }
 
-void WtsSessionProcessLauncher::DrainJobNotifications() {
-  DCHECK(ipc_message_loop_->BelongsToCurrentThread());
+void InJobLauncher::DrainJobNotifications() {
+  DCHECK(ipc_task_runner_->BelongsToCurrentThread());
 
   // DrainJobNotifications() is posted after the job object is destroyed, so
   // by this time all notifications from the job object have been processed
   // already. Let the main thread know that the queue has been drained.
-  main_message_loop_->PostTask(FROM_HERE, base::Bind(
-      &WtsSessionProcessLauncher::DrainJobNotificationsCompleted,
-      base::Unretained(this)));
+  main_task_runner_->PostTask(FROM_HERE, base::Bind(
+      &InJobLauncher::DrainJobNotificationsCompleted, this));
 }
 
-void WtsSessionProcessLauncher::DrainJobNotificationsCompleted() {
-  DCHECK(main_message_loop_->BelongsToCurrentThread());
-  DCHECK_EQ(job_state_, kJobStopping);
+void InJobLauncher::DrainJobNotificationsCompleted() {
+  DCHECK(main_task_runner_->BelongsToCurrentThread());
+
+  if (job_.IsValid()) {
+    job_.Close();
 
-  job_state_ = kJobStopped;
-  Stop();
+    // Drain the completion queue to make sure all job object notification have
+    // been received.
+    ipc_task_runner_->PostTask(FROM_HERE, base::Bind(
+        &InJobLauncher::DrainJobNotifications, this));
+  }
 }
 
-void WtsSessionProcessLauncher::InitializeJob() {
-  DCHECK(ipc_message_loop_->BelongsToCurrentThread());
+void InJobLauncher::InitializeJob() {
+  DCHECK(ipc_task_runner_->BelongsToCurrentThread());
 
   ScopedHandle job;
   job.Set(CreateJobObject(NULL, NULL));
@@ -332,25 +498,21 @@ void WtsSessionProcessLauncher::InitializeJob() {
   *job_wrapper = job.Pass();
 
   // Let the main thread know that initialization is complete.
-  main_message_loop_->PostTask(FROM_HERE, base::Bind(
-      &WtsSessionProcessLauncher::InitializeJobCompleted,
-      base::Unretained(this), base::Passed(&job_wrapper)));
+  main_task_runner_->PostTask(FROM_HERE, base::Bind(
+      &InJobLauncher::InitializeJobCompleted, this,
+      base::Passed(&job_wrapper)));
 }
 
-void WtsSessionProcessLauncher::InitializeJobCompleted(
+void InJobLauncher::InitializeJobCompleted(
     scoped_ptr<ScopedHandle> job) {
-  DCHECK(main_message_loop_->BelongsToCurrentThread());
+  DCHECK(main_task_runner_->BelongsToCurrentThread());
   DCHECK(!job_.IsValid());
-  DCHECK_EQ(job_state_, kJobUninitialized);
 
-  if (stoppable_state() == Stoppable::kRunning) {
-    job_ = job->Pass();
-    job_state_ = kJobRunning;
-  }
+  job_ = job->Pass();
 }
 
-void WtsSessionProcessLauncher::OnJobNotification(DWORD message, DWORD pid) {
-  DCHECK(main_message_loop_->BelongsToCurrentThread());
+void InJobLauncher::OnJobNotification(DWORD message, DWORD pid) {
+  DCHECK(main_task_runner_->BelongsToCurrentThread());
 
   switch (message) {
     case JOB_OBJECT_MSG_ACTIVE_PROCESS_ZERO:
@@ -366,6 +528,126 @@ void WtsSessionProcessLauncher::OnJobNotification(DWORD message, DWORD pid) {
   }
 }
 
+}  // namespace
+
+WtsProcessLauncherImpl::~WtsProcessLauncherImpl() {
+}
+
+WtsSessionProcessLauncher::WtsSessionProcessLauncher(
+    const base::Closure& stopped_callback,
+    WtsConsoleMonitor* monitor,
+    scoped_refptr<base::SingleThreadTaskRunner> main_message_loop,
+    scoped_refptr<base::SingleThreadTaskRunner> ipc_message_loop)
+    : Stoppable(main_message_loop, stopped_callback),
+      attached_(false),
+      main_message_loop_(main_message_loop),
+      ipc_message_loop_(ipc_message_loop),
+      monitor_(monitor) {
+  monitor_->AddWtsConsoleObserver(this);
+
+  // Construct the host binary name.
+  FilePath dir_path;
+  if (!PathService::Get(base::DIR_EXE, &dir_path)) {
+    LOG(ERROR) << "Failed to get the executable file name.";
+    Stop();
+    return;
+  }
+  FilePath host_binary = dir_path.Append(kMe2meHostBinaryName);
+
+  // The workaround we use to launch a process in a not yet logged in session
+  // (see CreateRemoteSessionProcess()) on Windows XP/2K3 does not let us to
+  // assign the started process to a job. However on Vista+ we have to start
+  // the host via a helper process. The helper process calls ShellExecute() that
+  // does not work across the session boundary but it required to launch
+  // a binary specifying uiAccess='true' in its manifest.
+  //
+  // Below we choose which implementation of |WorkerProcessLauncher::Delegate|
+  // to use. A single process is launched on XP (since uiAccess='true' does not
+  // have effect any way). Vista+ utilizes a helper process and assign it to
+  // a job object to control it.
+  if (base::win::GetVersion() == base::win::VERSION_XP) {
+    impl_ = new SingleProcessLauncher(host_binary, main_message_loop);
+  } else {
+    impl_ = new InJobLauncher(host_binary, main_message_loop, ipc_message_loop);
+  }
+}
+
+WtsSessionProcessLauncher::~WtsSessionProcessLauncher() {
+  // Make sure that the object is completely stopped. The same check exists
+  // in Stoppable::~Stoppable() but this one helps us to fail early and
+  // predictably.
+  CHECK_EQ(stoppable_state(), Stoppable::kStopped);
+
+  monitor_->RemoveWtsConsoleObserver(this);
+
+  CHECK(!attached_);
+  CHECK(!timer_.IsRunning());
+}
+
+void WtsSessionProcessLauncher::OnChannelConnected() {
+  DCHECK(main_message_loop_->BelongsToCurrentThread());
+}
+
+bool WtsSessionProcessLauncher::OnMessageReceived(const IPC::Message& message) {
+  DCHECK(main_message_loop_->BelongsToCurrentThread());
+
+  return false;
+}
+
+void WtsSessionProcessLauncher::OnSessionAttached(uint32 session_id) {
+  DCHECK(main_message_loop_->BelongsToCurrentThread());
+
+  if (stoppable_state() != Stoppable::kRunning) {
+    return;
+  }
+
+  DCHECK(!attached_);
+  DCHECK(!timer_.IsRunning());
+
+  attached_ = true;
+
+  // Create a session token and launch the host.
+  base::win::ScopedHandle session_token;
+  if (CreateSessionToken(session_id, &session_token) &&
+      impl_->SetSessionToken(session_token)) {
+    LaunchProcess();
+  }
+}
+
+void WtsSessionProcessLauncher::OnSessionDetached() {
+  DCHECK(main_message_loop_->BelongsToCurrentThread());
+  DCHECK(attached_);
+
+  attached_ = false;
+  launch_backoff_ = base::TimeDelta();
+  timer_.Stop();
+
+  if (launcher_.get() != NULL) {
+    launcher_->Stop();
+  }
+}
+
+void WtsSessionProcessLauncher::DoStop() {
+  DCHECK(main_message_loop_->BelongsToCurrentThread());
+
+  if (attached_) {
+    OnSessionDetached();
+  }
+
+  // Don't complete shutdown if |launcher_| is not completely stopped.
+  if (launcher_.get() != NULL) {
+    return;
+  }
+
+  // Tear down the core asynchromously.
+  if (impl_.get()) {
+    impl_->Stop();

[Wez, 2012/09/14 23:36:18]

nit: Stop() doesn't seem to actually stop anything; rename it Cleanup(),
perhaps?

[alexeypa (please no reviews), 2012/09/18 16:58:06]

It does "stop" job object notification. I'd like to call it Stop for parity with
other asynchronous objects.

+    impl_ = NULL;
+  }
+
+  CompleteStopping();
+}
+
 void WtsSessionProcessLauncher::LaunchProcess() {
   DCHECK(main_message_loop_->BelongsToCurrentThread());
   DCHECK(attached_);
@@ -374,7 +656,7 @@ void WtsSessionProcessLauncher::LaunchProcess() {
 
   launch_time_ = base::Time::Now();
   launcher_.reset(new WorkerProcessLauncher(
-      this, this,
+      impl_.get(), this,
       base::Bind(&WtsSessionProcessLauncher::OnLauncherStopped,
                  base::Unretained(this)),
       main_message_loop_,
@@ -385,16 +667,8 @@ void WtsSessionProcessLauncher::LaunchProcess() {
 void WtsSessionProcessLauncher::OnLauncherStopped() {
   DCHECK(main_message_loop_->BelongsToCurrentThread());
 
-  DWORD exit_code = CONTROL_C_EXIT;
-  if (worker_process_.IsValid()) {
-    if (!::GetExitCodeProcess(worker_process_, &exit_code)) {
-      LOG_GETLASTERROR(INFO)
-          << "Failed to query the exit code of the worker process";
-      exit_code = CONTROL_C_EXIT;
-    }
-
-    worker_process_.Close();
-  }
+  // Retrieve the exit code of the worker process.
+  DWORD exit_code = impl_->GetExitCode();
 
   launcher_.reset(NULL);