summaryrefslogtreecommitdiffstats
path: root/chrome/browser/process_singleton_win.cc
blob: d8073c1c8fbce0bee9f76be34fc59d02e4b237a8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
// 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/process_singleton.h"

#include <shellapi.h>
#include <shobjidl.h>

#include "base/base_paths.h"
#include "base/command_line.h"
#include "base/file_path.h"
#include "base/path_service.h"
#include "base/process_util.h"
#include "base/stringprintf.h"
#include "base/utf_string_conversions.h"
#include "base/win/metro.h"
#include "base/win/registry.h"
#include "base/win/scoped_com_initializer.h"
#include "base/win/scoped_comptr.h"
#include "base/win/scoped_handle.h"
#include "base/win/win_util.h"
#include "base/win/windows_version.h"
#include "base/win/wrapped_window_proc.h"
#include "chrome/browser/browser_process.h"
#include "chrome/browser/shell_integration.h"
#include "chrome/browser/ui/simple_message_box.h"
#include "chrome/common/chrome_constants.h"
#include "chrome/common/chrome_paths.h"
#include "chrome/common/chrome_paths_internal.h"
#include "chrome/common/chrome_switches.h"
#include "chrome/installer/util/browser_distribution.h"
#include "chrome/installer/util/install_util.h"
#include "chrome/installer/util/shell_util.h"
#include "chrome/installer/util/wmi.h"
#include "content/public/common/result_codes.h"
#include "grit/chromium_strings.h"
#include "grit/generated_resources.h"
#include "net/base/escape.h"
#include "ui/base/l10n/l10n_util.h"
#include "ui/base/win/hwnd_util.h"

namespace {

const char kLockfile[] = "lockfile";

const char kSearchUrl[] =
  "http://www.google.com/search?q=%s&sourceid=chrome&ie=UTF-8";

const int kMetroChromeActivationTimeoutMs = 3000;

// A helper class that acquires the given |mutex| while the AutoLockMutex is in
// scope.
class AutoLockMutex {
 public:
  explicit AutoLockMutex(HANDLE mutex) : mutex_(mutex) {
    DWORD result = WaitForSingleObject(mutex_, INFINITE);
    DPCHECK(result == WAIT_OBJECT_0) << "Result = " << result;
  }

  ~AutoLockMutex() {
    BOOL released = ReleaseMutex(mutex_);
    DPCHECK(released);
  }

 private:
  HANDLE mutex_;
  DISALLOW_COPY_AND_ASSIGN(AutoLockMutex);
};

// A helper class that releases the given |mutex| while the AutoUnlockMutex is
// in scope and immediately re-acquires it when going out of scope.
class AutoUnlockMutex {
 public:
  explicit AutoUnlockMutex(HANDLE mutex) : mutex_(mutex) {
    BOOL released = ReleaseMutex(mutex_);
    DPCHECK(released);
  }

  ~AutoUnlockMutex() {
    DWORD result = WaitForSingleObject(mutex_, INFINITE);
    DPCHECK(result == WAIT_OBJECT_0) << "Result = " << result;
  }

 private:
  HANDLE mutex_;
  DISALLOW_COPY_AND_ASSIGN(AutoUnlockMutex);
};

// Checks the visibility of the enumerated window and signals once a visible
// window has been found.
BOOL CALLBACK BrowserWindowEnumeration(HWND window, LPARAM param) {
  bool* result = reinterpret_cast<bool*>(param);
  *result = IsWindowVisible(window) != 0;
  // Stops enumeration if a visible window has been found.
  return !*result;
}

// This function thunks to the object's version of the windowproc, taking in
// consideration that there are several messages being dispatched before
// WM_NCCREATE which we let windows handle.
LRESULT CALLBACK ThunkWndProc(HWND hwnd, UINT message,
                              WPARAM wparam, LPARAM lparam) {
  ProcessSingleton* singleton =
      reinterpret_cast<ProcessSingleton*>(ui::GetWindowUserData(hwnd));
  if (message == WM_NCCREATE) {
    CREATESTRUCT* cs = reinterpret_cast<CREATESTRUCT*>(lparam);
    singleton = reinterpret_cast<ProcessSingleton*>(cs->lpCreateParams);
    CHECK(singleton);
    ui::SetWindowUserData(hwnd, singleton);
  } else if (!singleton) {
    return ::DefWindowProc(hwnd, message, wparam, lparam);
  }
  return singleton->WndProc(hwnd, message, wparam, lparam);
}

bool ParseCommandLine(const COPYDATASTRUCT* cds,
                      CommandLine* parsed_command_line,
                      FilePath* current_directory) {
  // We should have enough room for the shortest command (min_message_size)
  // and also be a multiple of wchar_t bytes. The shortest command
  // possible is L"START\0\0" (empty current directory and command line).
  static const int min_message_size = 7;
  if (cds->cbData < min_message_size * sizeof(wchar_t) ||
      cds->cbData % sizeof(wchar_t) != 0) {
    LOG(WARNING) << "Invalid WM_COPYDATA, length = " << cds->cbData;
    return false;
  }

  // We split the string into 4 parts on NULLs.
  DCHECK(cds->lpData);
  const std::wstring msg(static_cast<wchar_t*>(cds->lpData),
                         cds->cbData / sizeof(wchar_t));
  const std::wstring::size_type first_null = msg.find_first_of(L'\0');
  if (first_null == 0 || first_null == std::wstring::npos) {
    // no NULL byte, don't know what to do
    LOG(WARNING) << "Invalid WM_COPYDATA, length = " << msg.length() <<
      ", first null = " << first_null;
    return false;
  }

  // Decode the command, which is everything until the first NULL.
  if (msg.substr(0, first_null) == L"START") {
    // Another instance is starting parse the command line & do what it would
    // have done.
    VLOG(1) << "Handling STARTUP request from another process";
    const std::wstring::size_type second_null =
        msg.find_first_of(L'\0', first_null + 1);
    if (second_null == std::wstring::npos ||
        first_null == msg.length() - 1 || second_null == msg.length()) {
      LOG(WARNING) << "Invalid format for start command, we need a string in 4 "
        "parts separated by NULLs";
      return false;
    }

    // Get current directory.
    *current_directory = FilePath(msg.substr(first_null + 1,
                                             second_null - first_null));

    const std::wstring::size_type third_null =
        msg.find_first_of(L'\0', second_null + 1);
    if (third_null == std::wstring::npos ||
        third_null == msg.length()) {
      LOG(WARNING) << "Invalid format for start command, we need a string in 4 "
        "parts separated by NULLs";
    }

    // Get command line.
    const std::wstring cmd_line =
        msg.substr(second_null + 1, third_null - second_null);
    *parsed_command_line = CommandLine::FromString(cmd_line);
    return true;
  }
  return false;
}

bool ActivateMetroChrome() {
  FilePath chrome_exe;
  if (!PathService::Get(base::FILE_EXE, &chrome_exe)) {
    NOTREACHED() << "Failed to get chrome exe path";
    return false;
  }
  string16 app_id = ShellUtil::GetBrowserModelId(
      BrowserDistribution::GetDistribution(),
      InstallUtil::IsPerUserInstall(chrome_exe.value().c_str()));
  if (app_id.empty()) {
    NOTREACHED() << "Failed to get chrome app user model id.";
    return false;
  }

  base::win::ScopedComPtr<IApplicationActivationManager> activation_manager;
  HRESULT hr = activation_manager.CreateInstance(
      CLSID_ApplicationActivationManager);
  if (!activation_manager) {
    NOTREACHED() << "Failed to cocreate activation manager. Error: " << hr;
    return false;
  }

  unsigned long pid = 0;
  hr = activation_manager->ActivateApplication(app_id.c_str(),
                                               L"open",
                                               AO_NONE,
                                               &pid);
  if (FAILED(hr)) {
    NOTREACHED() << "Failed to activate metro chrome. Error: " << hr;
    return false;
  }
  return true;
}

// Returns true if Chrome needs to be relaunched into Windows 8 immersive mode.
// Following conditions apply:-
// 1. Windows 8 or greater.
// 2. Not in Windows 8 immersive mode.
// 3. Chrome is default browser.
// 4. Process integrity level is not high.
// 5. The profile data directory is the default directory.
// 6. Last used mode was immersive/machine is a tablet.
// TODO(ananta)
// Move this function to a common place as the Windows 8 delegate_execute
// handler can possibly use this.
bool ShouldLaunchInWindows8ImmersiveMode(const FilePath& user_data_dir) {
#if defined(USE_AURA)
  return false;
#endif

  if (base::win::GetVersion() < base::win::VERSION_WIN8)
    return false;

  if (base::win::IsProcessImmersive(base::GetCurrentProcessHandle()))
    return false;

  if (ShellIntegration::GetDefaultBrowser() != ShellIntegration::IS_DEFAULT)
    return false;

  base::IntegrityLevel integrity_level = base::INTEGRITY_UNKNOWN;
  base::GetProcessIntegrityLevel(base::GetCurrentProcessHandle(),
                                 &integrity_level);
  if (integrity_level == base::HIGH_INTEGRITY)
    return false;

  FilePath default_user_data_dir;
  if (!chrome::GetDefaultUserDataDirectory(&default_user_data_dir))
    return false;

  if (default_user_data_dir != user_data_dir)
    return false;

  base::win::RegKey reg_key;
  DWORD reg_value = 0;
  if (reg_key.Create(HKEY_CURRENT_USER, chrome::kMetroRegistryPath,
                     KEY_READ) == ERROR_SUCCESS &&
      reg_key.ReadValueDW(chrome::kLaunchModeValue,
                          &reg_value) == ERROR_SUCCESS) {
    return reg_value == 1;
  }
  return base::win::IsMachineATablet();
}

}  // namespace

// Microsoft's Softricity virtualization breaks the sandbox processes.
// So, if we detect the Softricity DLL we use WMI Win32_Process.Create to
// break out of the virtualization environment.
// http://code.google.com/p/chromium/issues/detail?id=43650
bool ProcessSingleton::EscapeVirtualization(const FilePath& user_data_dir) {
  if (::GetModuleHandle(L"sftldr_wow64.dll") ||
      ::GetModuleHandle(L"sftldr.dll")) {
    int process_id;
    if (!installer::WMIProcess::Launch(GetCommandLineW(), &process_id))
      return false;
    is_virtualized_ = true;
    // The new window was spawned from WMI, and won't be in the foreground.
    // So, first we sleep while the new chrome.exe instance starts (because
    // WaitForInputIdle doesn't work here). Then we poll for up to two more
    // seconds and make the window foreground if we find it (or we give up).
    HWND hwnd = 0;
    ::Sleep(90);
    for (int tries = 200; tries; --tries) {
      hwnd = FindWindowEx(HWND_MESSAGE, NULL, chrome::kMessageWindowClass,
                          user_data_dir.value().c_str());
      if (hwnd) {
        ::SetForegroundWindow(hwnd);
        break;
      }
      ::Sleep(10);
    }
    return true;
  }
  return false;
}

ProcessSingleton::ProcessSingleton(const FilePath& user_data_dir)
    : window_(NULL), locked_(false), foreground_window_(NULL),
      is_virtualized_(false), lock_file_(INVALID_HANDLE_VALUE),
      user_data_dir_(user_data_dir) {
}

ProcessSingleton::~ProcessSingleton() {
  // We need to unregister the window as late as possible so that we can detect
  // another instance of chrome running. Otherwise we may end up writing out
  // data while a new chrome is starting up.
  if (window_) {
    ::DestroyWindow(window_);
    ::UnregisterClass(chrome::kMessageWindowClass,
                      base::GetModuleFromAddress(&ThunkWndProc));
  }
  if (lock_file_ != INVALID_HANDLE_VALUE)
    CloseHandle(lock_file_);
}

// Code roughly based on Mozilla.
ProcessSingleton::NotifyResult ProcessSingleton::NotifyOtherProcess() {
  if (is_virtualized_)
    return PROCESS_NOTIFIED;  // We already spawned the process in this case.
  if (lock_file_ == INVALID_HANDLE_VALUE && !remote_window_) {
    return LOCK_ERROR;
  } else if (!remote_window_) {
    return PROCESS_NONE;
  }

  DWORD process_id = 0;
  DWORD thread_id = GetWindowThreadProcessId(remote_window_, &process_id);
  // It is possible that the process owning this window may have died by now.
  if (!thread_id || !process_id) {
    remote_window_ = NULL;
    return PROCESS_NONE;
  }

  if (base::win::IsMetroProcess()) {
    // Interesting corner case. We are launched as a metro process but we
    // found another chrome running. Since metro enforces single instance then
    // the other chrome must be desktop chrome and this must be a search charm
    // activation. This scenario is unique; other cases should be properly
    // handled by the delegate_execute which will not activate a second chrome.
    string16 terms;
    base::win::MetroLaunchType launch = base::win::GetMetroLaunchParams(&terms);
    if (launch != base::win::METRO_SEARCH) {
      LOG(WARNING) << "In metro mode, but and launch is " << launch;
    } else {
      std::string query = net::EscapeQueryParamValue(UTF16ToUTF8(terms), true);
      std::string url = base::StringPrintf(kSearchUrl, query.c_str());
      SHELLEXECUTEINFOA sei = { sizeof(sei) };
      sei.fMask = SEE_MASK_FLAG_LOG_USAGE;
      sei.nShow = SW_SHOWNORMAL;
      sei.lpFile = url.c_str();
      OutputDebugStringA(sei.lpFile);
      sei.lpDirectory = "";
      ::ShellExecuteExA(&sei);
    }
    return PROCESS_NOTIFIED;
  }

  // Non-metro mode, send our command line to the other chrome message window.
  // format is "START\0<<<current directory>>>\0<<<commandline>>>".
  std::wstring to_send(L"START\0", 6);  // want the NULL in the string.
  FilePath cur_dir;
  if (!PathService::Get(base::DIR_CURRENT, &cur_dir))
    return PROCESS_NONE;
  to_send.append(cur_dir.value());
  to_send.append(L"\0", 1);  // Null separator.
  to_send.append(GetCommandLineW());
  to_send.append(L"\0", 1);  // Null separator.

  base::win::ScopedHandle process_handle;
  if (base::win::GetVersion() >= base::win::VERSION_WIN8 &&
      base::OpenProcessHandleWithAccess(
          process_id, PROCESS_QUERY_INFORMATION,
          process_handle.Receive()) &&
      base::win::IsProcessImmersive(process_handle.Get())) {
    ActivateMetroChrome();
  }

  // Allow the current running browser window making itself the foreground
  // window (otherwise it will just flash in the taskbar).
  AllowSetForegroundWindow(process_id);

  COPYDATASTRUCT cds;
  cds.dwData = 0;
  cds.cbData = static_cast<DWORD>((to_send.length() + 1) * sizeof(wchar_t));
  cds.lpData = const_cast<wchar_t*>(to_send.c_str());
  DWORD_PTR result = 0;
  if (SendMessageTimeout(remote_window_,
                         WM_COPYDATA,
                         NULL,
                         reinterpret_cast<LPARAM>(&cds),
                         SMTO_ABORTIFHUNG,
                         kTimeoutInSeconds * 1000,
                         &result)) {
    // It is possible that the process owning this window may have died by now.
    if (!result) {
      remote_window_ = NULL;
      return PROCESS_NONE;
    }
    return PROCESS_NOTIFIED;
  }

  // It is possible that the process owning this window may have died by now.
  if (!IsWindow(remote_window_)) {
    remote_window_ = NULL;
    return PROCESS_NONE;
  }

  // The window is hung. Scan for every window to find a visible one.
  bool visible_window = false;
  EnumThreadWindows(thread_id,
                    &BrowserWindowEnumeration,
                    reinterpret_cast<LPARAM>(&visible_window));

  // If there is a visible browser window, ask the user before killing it.
  if (visible_window && chrome::ShowMessageBox(NULL,
      l10n_util::GetStringUTF16(IDS_PRODUCT_NAME),
      l10n_util::GetStringUTF16(IDS_BROWSER_HUNGBROWSER_MESSAGE),
      chrome::MESSAGE_BOX_TYPE_QUESTION) == chrome::MESSAGE_BOX_RESULT_NO) {
    // The user denied. Quit silently.
    return PROCESS_NOTIFIED;
  }

  // Time to take action. Kill the browser process.
  base::KillProcessById(process_id, content::RESULT_CODE_HUNG, true);
  remote_window_ = NULL;
  return PROCESS_NONE;
}

ProcessSingleton::NotifyResult ProcessSingleton::NotifyOtherProcessOrCreate(
    const NotificationCallback& notification_callback) {
  ProcessSingleton::NotifyResult result = PROCESS_NONE;
  if (!Create(notification_callback)) {
    result = NotifyOtherProcess();
    if (result == PROCESS_NONE)
      result = PROFILE_IN_USE;
  } else {
    g_browser_process->PlatformSpecificCommandLineProcessing(
        *CommandLine::ForCurrentProcess());
  }
  return result;
}

// Look for a Chrome instance that uses the same profile directory. If there
// isn't one, create a message window with its title set to the profile
// directory path.
bool ProcessSingleton::Create(
    const NotificationCallback& notification_callback) {
  DCHECK(notification_callback_.is_null());

  static const wchar_t kMutexName[] = L"Local\\ChromeProcessSingletonStartup!";
  static const wchar_t kMetroActivationEventName[] =
      L"Local\\ChromeProcessSingletonStartupMetroActivation!";

  remote_window_ = FindWindowEx(HWND_MESSAGE, NULL,
                                chrome::kMessageWindowClass,
                                user_data_dir_.value().c_str());
  if (!remote_window_ && !EscapeVirtualization(user_data_dir_)) {
    // Make sure we will be the one and only process creating the window.
    // We use a named Mutex since we are protecting against multi-process
    // access. As documented, it's clearer to NOT request ownership on creation
    // since it isn't guaranteed we will get it. It is better to create it
    // without ownership and explicitly get the ownership afterward.
    base::win::ScopedHandle only_me(CreateMutex(NULL, FALSE, kMutexName));
    DPCHECK(only_me.IsValid());

    AutoLockMutex auto_lock_only_me(only_me);

    // We now own the mutex so we are the only process that can create the
    // window at this time, but we must still check if someone created it
    // between the time where we looked for it above and the time the mutex
    // was given to us.
    remote_window_ = FindWindowEx(HWND_MESSAGE, NULL,
                                  chrome::kMessageWindowClass,
                                  user_data_dir_.value().c_str());


    // In Win8+, a new Chrome process launched in Desktop mode may need to be
    // transmuted into Metro Chrome (see ShouldLaunchInWindows8ImmersiveMode for
    // heuristics). To accomplish this, the current Chrome activates Metro
    // Chrome, releases the startup mutex, and waits for metro Chrome to take
    // the singleton. From that point onward, the command line for this Chrome
    // process will be sent to Metro Chrome by the usual channels.
    if (!remote_window_ && base::win::GetVersion() >= base::win::VERSION_WIN8 &&
        !base::win::IsMetroProcess()) {
      // |metro_activation_event| is created right before activating a Metro
      // Chrome (note that there can only be one Metro Chrome process; by OS
      // design); all following Desktop processes will then wait for this event
      // to be signaled by Metro Chrome which will do so as soon as it grabs
      // this singleton (should any of the waiting processes timeout waiting for
      // the signal they will try to grab the singleton for themselves which
      // will result in a forced Desktop Chrome launch in the worst case).
      base::win::ScopedHandle metro_activation_event(
          OpenEvent(SYNCHRONIZE, FALSE, kMetroActivationEventName));
      if (!metro_activation_event.IsValid() &&
          ShouldLaunchInWindows8ImmersiveMode(user_data_dir_)) {
        // No Metro activation is under way, but the desire is to launch in
        // Metro mode: activate and rendez-vous with the activated process.
        metro_activation_event.Set(
            CreateEvent(NULL, TRUE, FALSE, kMetroActivationEventName));
        if (!ActivateMetroChrome()) {
          // Failed to launch immersive Chrome, default to launching on Desktop.
          LOG(ERROR) << "Failed to launch immersive chrome";
          metro_activation_event.Close();
        }
      }

      if (metro_activation_event.IsValid()) {
        // Release |only_me| (to let Metro Chrome grab this singleton) and wait
        // until the event is signaled (i.e. Metro Chrome was successfully
        // activated). Ignore timeout waiting for |metro_activation_event|.
        {
          AutoUnlockMutex auto_unlock_only_me(only_me);

          DWORD result = WaitForSingleObject(metro_activation_event,
                                             kMetroChromeActivationTimeoutMs);
          DPCHECK(result == WAIT_OBJECT_0 || result == WAIT_TIMEOUT)
              << "Result = " << result;
        }

        // Check if this singleton was successfully grabbed by another process
        // (hopefully Metro Chrome). Failing to do so, this process will grab
        // the singleton and launch in Desktop mode.
        remote_window_ = FindWindowEx(HWND_MESSAGE, NULL,
                                      chrome::kMessageWindowClass,
                                      user_data_dir_.value().c_str());
      }
    }

    if (!remote_window_) {
      // We have to make sure there is no Chrome instance running on another
      // machine that uses the same profile.
      FilePath lock_file_path = user_data_dir_.AppendASCII(kLockfile);
      lock_file_ = CreateFile(lock_file_path.value().c_str(),
                              GENERIC_WRITE,
                              FILE_SHARE_READ,
                              NULL,
                              CREATE_ALWAYS,
                              FILE_ATTRIBUTE_NORMAL | FILE_FLAG_DELETE_ON_CLOSE,
                              NULL);
      DWORD error = GetLastError();
      LOG_IF(WARNING, lock_file_ != INVALID_HANDLE_VALUE &&
          error == ERROR_ALREADY_EXISTS) << "Lock file exists but is writable.";
      LOG_IF(ERROR, lock_file_ == INVALID_HANDLE_VALUE)
          << "Lock file can not be created! Error code: " << error;

      if (lock_file_ != INVALID_HANDLE_VALUE) {
        HINSTANCE hinst = base::GetModuleFromAddress(&ThunkWndProc);

        WNDCLASSEX wc = {0};
        wc.cbSize = sizeof(wc);
        wc.lpfnWndProc = base::win::WrappedWindowProc<ThunkWndProc>;
        wc.hInstance = hinst;
        wc.lpszClassName = chrome::kMessageWindowClass;
        ATOM clazz = ::RegisterClassEx(&wc);
        DCHECK(clazz);

        // Set the window's title to the path of our user data directory so
        // other Chrome instances can decide if they should forward to us.
        window_ = ::CreateWindow(MAKEINTATOM(clazz),
                                 user_data_dir_.value().c_str(),
                                 0, 0, 0, 0, 0, HWND_MESSAGE, 0, hinst, this);
        CHECK(window_);
      }

      if (base::win::GetVersion() >= base::win::VERSION_WIN8) {
        // Make sure no one is still waiting on Metro activation whether it
        // succeeded (i.e., this is the Metro process) or failed.
        base::win::ScopedHandle metro_activation_event(
            OpenEvent(EVENT_MODIFY_STATE, FALSE, kMetroActivationEventName));
        if (metro_activation_event.IsValid())
          SetEvent(metro_activation_event);
      }
    }
  }

  if (window_ != NULL)
    notification_callback_ = notification_callback;

  return window_ != NULL;
}

void ProcessSingleton::Cleanup() {
}

LRESULT ProcessSingleton::OnCopyData(HWND hwnd, const COPYDATASTRUCT* cds) {
  // If locked, it means we are not ready to process this message because
  // we are probably in a first run critical phase.
  if (locked_) {
#if defined(USE_AURA)
    NOTIMPLEMENTED();
#else
    // Attempt to place ourselves in the foreground / flash the task bar.
    if (foreground_window_ != NULL && IsWindow(foreground_window_)) {
      SetForegroundWindow(foreground_window_);
    } else {
      // Read the command line and store it. It will be replayed when the
      // ProcessSingleton becomes unlocked.
      CommandLine parsed_command_line(CommandLine::NO_PROGRAM);
      FilePath current_directory;
      if (ParseCommandLine(cds, &parsed_command_line, &current_directory))
        saved_startup_messages_.push_back(
            std::make_pair(parsed_command_line.argv(), current_directory));
    }
#endif
    return TRUE;
  }

  CommandLine parsed_command_line(CommandLine::NO_PROGRAM);
  FilePath current_directory;
  if (!ParseCommandLine(cds, &parsed_command_line, &current_directory))
    return TRUE;
  return notification_callback_.Run(parsed_command_line, current_directory) ?
      TRUE : FALSE;
}

LRESULT ProcessSingleton::WndProc(HWND hwnd, UINT message,
                                  WPARAM wparam, LPARAM lparam) {
  switch (message) {
    case WM_COPYDATA:
      return OnCopyData(reinterpret_cast<HWND>(wparam),
                        reinterpret_cast<COPYDATASTRUCT*>(lparam));
    default:
      break;
  }

  return ::DefWindowProc(hwnd, message, wparam, lparam);
}