Adding upstream version 86.0.1.upstream/86.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2272 insertions, 0 deletions

diff --git a/widget/windows/WinUtils.cpp b/widget/windows/WinUtils.cpp
new file mode 100644
index 0000000000..14706d86a4
--- /dev/null
+++ b/widget/windows/WinUtils.cpp
@@ -0,0 +1,2272 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sts=2 sw=2 et cin: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "WinUtils.h"
+
+#include <knownfolders.h>
+#include <winioctl.h>
+
+#include "GeckoProfiler.h"
+#include "gfxPlatform.h"
+#include "gfxUtils.h"
+#include "nsWindow.h"
+#include "nsWindowDefs.h"
+#include "InputDeviceUtils.h"
+#include "KeyboardLayout.h"
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/BackgroundHangMonitor.h"
+#include "mozilla/ClearOnShutdown.h"
+#include "mozilla/dom/MouseEventBinding.h"
+#include "mozilla/gfx/2D.h"
+#include "mozilla/gfx/DataSurfaceHelpers.h"
+#include "mozilla/gfx/Logging.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/SchedulerGroup.h"
+#include "mozilla/WindowsVersion.h"
+#include "mozilla/Unused.h"
+#include "nsIContentPolicy.h"
+#include "nsIWindowsUIUtils.h"
+#include "nsContentUtils.h"
+
+#include "mozilla/Logging.h"
+
+#include "nsString.h"
+#include "nsDirectoryServiceUtils.h"
+#include "imgIContainer.h"
+#include "imgITools.h"
+#include "nsNetUtil.h"
+#include "nsIOutputStream.h"
+#include "nsNetCID.h"
+#include "prtime.h"
+#ifdef MOZ_PLACES
+#  include "nsIFaviconService.h"
+#endif
+#include "nsIDownloader.h"
+#include "nsIChannel.h"
+#include "nsIThread.h"
+#include "MainThreadUtils.h"
+#include "nsLookAndFeel.h"
+#include "nsUnicharUtils.h"
+#include "nsWindowsHelpers.h"
+#include "WinContentSystemParameters.h"
+
+#include <textstor.h>
+#include "TSFTextStore.h"
+
+#include <shlobj.h>
+#include <shlwapi.h>
+
+mozilla::LazyLogModule gWindowsLog("Widget");
+
+#define LOG_E(...) MOZ_LOG(gWindowsLog, LogLevel::Error, (__VA_ARGS__))
+#define LOG_D(...) MOZ_LOG(gWindowsLog, LogLevel::Debug, (__VA_ARGS__))
+
+using namespace mozilla::gfx;
+
+namespace mozilla {
+namespace widget {
+
+#define ENTRY(_msg) \
+  { #_msg, _msg }
+EventMsgInfo gAllEvents[] = {ENTRY(WM_NULL),
+                             ENTRY(WM_CREATE),
+                             ENTRY(WM_DESTROY),
+                             ENTRY(WM_MOVE),
+                             ENTRY(WM_SIZE),
+                             ENTRY(WM_ACTIVATE),
+                             ENTRY(WM_SETFOCUS),
+                             ENTRY(WM_KILLFOCUS),
+                             ENTRY(WM_ENABLE),
+                             ENTRY(WM_SETREDRAW),
+                             ENTRY(WM_SETTEXT),
+                             ENTRY(WM_GETTEXT),
+                             ENTRY(WM_GETTEXTLENGTH),
+                             ENTRY(WM_PAINT),
+                             ENTRY(WM_CLOSE),
+                             ENTRY(WM_QUERYENDSESSION),
+                             ENTRY(WM_QUIT),
+                             ENTRY(WM_QUERYOPEN),
+                             ENTRY(WM_ERASEBKGND),
+                             ENTRY(WM_SYSCOLORCHANGE),
+                             ENTRY(WM_ENDSESSION),
+                             ENTRY(WM_SHOWWINDOW),
+                             ENTRY(WM_SETTINGCHANGE),
+                             ENTRY(WM_DEVMODECHANGE),
+                             ENTRY(WM_ACTIVATEAPP),
+                             ENTRY(WM_FONTCHANGE),
+                             ENTRY(WM_TIMECHANGE),
+                             ENTRY(WM_CANCELMODE),
+                             ENTRY(WM_SETCURSOR),
+                             ENTRY(WM_MOUSEACTIVATE),
+                             ENTRY(WM_CHILDACTIVATE),
+                             ENTRY(WM_QUEUESYNC),
+                             ENTRY(WM_GETMINMAXINFO),
+                             ENTRY(WM_PAINTICON),
+                             ENTRY(WM_ICONERASEBKGND),
+                             ENTRY(WM_NEXTDLGCTL),
+                             ENTRY(WM_SPOOLERSTATUS),
+                             ENTRY(WM_DRAWITEM),
+                             ENTRY(WM_MEASUREITEM),
+                             ENTRY(WM_DELETEITEM),
+                             ENTRY(WM_VKEYTOITEM),
+                             ENTRY(WM_CHARTOITEM),
+                             ENTRY(WM_SETFONT),
+                             ENTRY(WM_GETFONT),
+                             ENTRY(WM_SETHOTKEY),
+                             ENTRY(WM_GETHOTKEY),
+                             ENTRY(WM_QUERYDRAGICON),
+                             ENTRY(WM_COMPAREITEM),
+                             ENTRY(WM_GETOBJECT),
+                             ENTRY(WM_COMPACTING),
+                             ENTRY(WM_COMMNOTIFY),
+                             ENTRY(WM_WINDOWPOSCHANGING),
+                             ENTRY(WM_WINDOWPOSCHANGED),
+                             ENTRY(WM_POWER),
+                             ENTRY(WM_COPYDATA),
+                             ENTRY(WM_CANCELJOURNAL),
+                             ENTRY(WM_NOTIFY),
+                             ENTRY(WM_INPUTLANGCHANGEREQUEST),
+                             ENTRY(WM_INPUTLANGCHANGE),
+                             ENTRY(WM_TCARD),
+                             ENTRY(WM_HELP),
+                             ENTRY(WM_USERCHANGED),
+                             ENTRY(WM_NOTIFYFORMAT),
+                             ENTRY(WM_CONTEXTMENU),
+                             ENTRY(WM_STYLECHANGING),
+                             ENTRY(WM_STYLECHANGED),
+                             ENTRY(WM_DISPLAYCHANGE),
+                             ENTRY(WM_GETICON),
+                             ENTRY(WM_SETICON),
+                             ENTRY(WM_NCCREATE),
+                             ENTRY(WM_NCDESTROY),
+                             ENTRY(WM_NCCALCSIZE),
+                             ENTRY(WM_NCHITTEST),
+                             ENTRY(WM_NCPAINT),
+                             ENTRY(WM_NCACTIVATE),
+                             ENTRY(WM_GETDLGCODE),
+                             ENTRY(WM_SYNCPAINT),
+                             ENTRY(WM_NCMOUSEMOVE),
+                             ENTRY(WM_NCLBUTTONDOWN),
+                             ENTRY(WM_NCLBUTTONUP),
+                             ENTRY(WM_NCLBUTTONDBLCLK),
+                             ENTRY(WM_NCRBUTTONDOWN),
+                             ENTRY(WM_NCRBUTTONUP),
+                             ENTRY(WM_NCRBUTTONDBLCLK),
+                             ENTRY(WM_NCMBUTTONDOWN),
+                             ENTRY(WM_NCMBUTTONUP),
+                             ENTRY(WM_NCMBUTTONDBLCLK),
+                             ENTRY(EM_GETSEL),
+                             ENTRY(EM_SETSEL),
+                             ENTRY(EM_GETRECT),
+                             ENTRY(EM_SETRECT),
+                             ENTRY(EM_SETRECTNP),
+                             ENTRY(EM_SCROLL),
+                             ENTRY(EM_LINESCROLL),
+                             ENTRY(EM_SCROLLCARET),
+                             ENTRY(EM_GETMODIFY),
+                             ENTRY(EM_SETMODIFY),
+                             ENTRY(EM_GETLINECOUNT),
+                             ENTRY(EM_LINEINDEX),
+                             ENTRY(EM_SETHANDLE),
+                             ENTRY(EM_GETHANDLE),
+                             ENTRY(EM_GETTHUMB),
+                             ENTRY(EM_LINELENGTH),
+                             ENTRY(EM_REPLACESEL),
+                             ENTRY(EM_GETLINE),
+                             ENTRY(EM_LIMITTEXT),
+                             ENTRY(EM_CANUNDO),
+                             ENTRY(EM_UNDO),
+                             ENTRY(EM_FMTLINES),
+                             ENTRY(EM_LINEFROMCHAR),
+                             ENTRY(EM_SETTABSTOPS),
+                             ENTRY(EM_SETPASSWORDCHAR),
+                             ENTRY(EM_EMPTYUNDOBUFFER),
+                             ENTRY(EM_GETFIRSTVISIBLELINE),
+                             ENTRY(EM_SETREADONLY),
+                             ENTRY(EM_SETWORDBREAKPROC),
+                             ENTRY(EM_GETWORDBREAKPROC),
+                             ENTRY(EM_GETPASSWORDCHAR),
+                             ENTRY(EM_SETMARGINS),
+                             ENTRY(EM_GETMARGINS),
+                             ENTRY(EM_GETLIMITTEXT),
+                             ENTRY(EM_POSFROMCHAR),
+                             ENTRY(EM_CHARFROMPOS),
+                             ENTRY(EM_SETIMESTATUS),
+                             ENTRY(EM_GETIMESTATUS),
+                             ENTRY(SBM_SETPOS),
+                             ENTRY(SBM_GETPOS),
+                             ENTRY(SBM_SETRANGE),
+                             ENTRY(SBM_SETRANGEREDRAW),
+                             ENTRY(SBM_GETRANGE),
+                             ENTRY(SBM_ENABLE_ARROWS),
+                             ENTRY(SBM_SETSCROLLINFO),
+                             ENTRY(SBM_GETSCROLLINFO),
+                             ENTRY(WM_KEYDOWN),
+                             ENTRY(WM_KEYUP),
+                             ENTRY(WM_CHAR),
+                             ENTRY(WM_DEADCHAR),
+                             ENTRY(WM_SYSKEYDOWN),
+                             ENTRY(WM_SYSKEYUP),
+                             ENTRY(WM_SYSCHAR),
+                             ENTRY(WM_SYSDEADCHAR),
+                             ENTRY(WM_KEYLAST),
+                             ENTRY(WM_IME_STARTCOMPOSITION),
+                             ENTRY(WM_IME_ENDCOMPOSITION),
+                             ENTRY(WM_IME_COMPOSITION),
+                             ENTRY(WM_INITDIALOG),
+                             ENTRY(WM_COMMAND),
+                             ENTRY(WM_SYSCOMMAND),
+                             ENTRY(WM_TIMER),
+                             ENTRY(WM_HSCROLL),
+                             ENTRY(WM_VSCROLL),
+                             ENTRY(WM_INITMENU),
+                             ENTRY(WM_INITMENUPOPUP),
+                             ENTRY(WM_MENUSELECT),
+                             ENTRY(WM_MENUCHAR),
+                             ENTRY(WM_ENTERIDLE),
+                             ENTRY(WM_MENURBUTTONUP),
+                             ENTRY(WM_MENUDRAG),
+                             ENTRY(WM_MENUGETOBJECT),
+                             ENTRY(WM_UNINITMENUPOPUP),
+                             ENTRY(WM_MENUCOMMAND),
+                             ENTRY(WM_CHANGEUISTATE),
+                             ENTRY(WM_UPDATEUISTATE),
+                             ENTRY(WM_CTLCOLORMSGBOX),
+                             ENTRY(WM_CTLCOLOREDIT),
+                             ENTRY(WM_CTLCOLORLISTBOX),
+                             ENTRY(WM_CTLCOLORBTN),
+                             ENTRY(WM_CTLCOLORDLG),
+                             ENTRY(WM_CTLCOLORSCROLLBAR),
+                             ENTRY(WM_CTLCOLORSTATIC),
+                             ENTRY(CB_GETEDITSEL),
+                             ENTRY(CB_LIMITTEXT),
+                             ENTRY(CB_SETEDITSEL),
+                             ENTRY(CB_ADDSTRING),
+                             ENTRY(CB_DELETESTRING),
+                             ENTRY(CB_DIR),
+                             ENTRY(CB_GETCOUNT),
+                             ENTRY(CB_GETCURSEL),
+                             ENTRY(CB_GETLBTEXT),
+                             ENTRY(CB_GETLBTEXTLEN),
+                             ENTRY(CB_INSERTSTRING),
+                             ENTRY(CB_RESETCONTENT),
+                             ENTRY(CB_FINDSTRING),
+                             ENTRY(CB_SELECTSTRING),
+                             ENTRY(CB_SETCURSEL),
+                             ENTRY(CB_SHOWDROPDOWN),
+                             ENTRY(CB_GETITEMDATA),
+                             ENTRY(CB_SETITEMDATA),
+                             ENTRY(CB_GETDROPPEDCONTROLRECT),
+                             ENTRY(CB_SETITEMHEIGHT),
+                             ENTRY(CB_GETITEMHEIGHT),
+                             ENTRY(CB_SETEXTENDEDUI),
+                             ENTRY(CB_GETEXTENDEDUI),
+                             ENTRY(CB_GETDROPPEDSTATE),
+                             ENTRY(CB_FINDSTRINGEXACT),
+                             ENTRY(CB_SETLOCALE),
+                             ENTRY(CB_GETLOCALE),
+                             ENTRY(CB_GETTOPINDEX),
+                             ENTRY(CB_SETTOPINDEX),
+                             ENTRY(CB_GETHORIZONTALEXTENT),
+                             ENTRY(CB_SETHORIZONTALEXTENT),
+                             ENTRY(CB_GETDROPPEDWIDTH),
+                             ENTRY(CB_SETDROPPEDWIDTH),
+                             ENTRY(CB_INITSTORAGE),
+                             ENTRY(CB_MSGMAX),
+                             ENTRY(LB_ADDSTRING),
+                             ENTRY(LB_INSERTSTRING),
+                             ENTRY(LB_DELETESTRING),
+                             ENTRY(LB_SELITEMRANGEEX),
+                             ENTRY(LB_RESETCONTENT),
+                             ENTRY(LB_SETSEL),
+                             ENTRY(LB_SETCURSEL),
+                             ENTRY(LB_GETSEL),
+                             ENTRY(LB_GETCURSEL),
+                             ENTRY(LB_GETTEXT),
+                             ENTRY(LB_GETTEXTLEN),
+                             ENTRY(LB_GETCOUNT),
+                             ENTRY(LB_SELECTSTRING),
+                             ENTRY(LB_DIR),
+                             ENTRY(LB_GETTOPINDEX),
+                             ENTRY(LB_FINDSTRING),
+                             ENTRY(LB_GETSELCOUNT),
+                             ENTRY(LB_GETSELITEMS),
+                             ENTRY(LB_SETTABSTOPS),
+                             ENTRY(LB_GETHORIZONTALEXTENT),
+                             ENTRY(LB_SETHORIZONTALEXTENT),
+                             ENTRY(LB_SETCOLUMNWIDTH),
+                             ENTRY(LB_ADDFILE),
+                             ENTRY(LB_SETTOPINDEX),
+                             ENTRY(LB_GETITEMRECT),
+                             ENTRY(LB_GETITEMDATA),
+                             ENTRY(LB_SETITEMDATA),
+                             ENTRY(LB_SELITEMRANGE),
+                             ENTRY(LB_SETANCHORINDEX),
+                             ENTRY(LB_GETANCHORINDEX),
+                             ENTRY(LB_SETCARETINDEX),
+                             ENTRY(LB_GETCARETINDEX),
+                             ENTRY(LB_SETITEMHEIGHT),
+                             ENTRY(LB_GETITEMHEIGHT),
+                             ENTRY(LB_FINDSTRINGEXACT),
+                             ENTRY(LB_SETLOCALE),
+                             ENTRY(LB_GETLOCALE),
+                             ENTRY(LB_SETCOUNT),
+                             ENTRY(LB_INITSTORAGE),
+                             ENTRY(LB_ITEMFROMPOINT),
+                             ENTRY(LB_MSGMAX),
+                             ENTRY(WM_MOUSEMOVE),
+                             ENTRY(WM_LBUTTONDOWN),
+                             ENTRY(WM_LBUTTONUP),
+                             ENTRY(WM_LBUTTONDBLCLK),
+                             ENTRY(WM_RBUTTONDOWN),
+                             ENTRY(WM_RBUTTONUP),
+                             ENTRY(WM_RBUTTONDBLCLK),
+                             ENTRY(WM_MBUTTONDOWN),
+                             ENTRY(WM_MBUTTONUP),
+                             ENTRY(WM_MBUTTONDBLCLK),
+                             ENTRY(WM_MOUSEWHEEL),
+                             ENTRY(WM_MOUSEHWHEEL),
+                             ENTRY(WM_PARENTNOTIFY),
+                             ENTRY(WM_ENTERMENULOOP),
+                             ENTRY(WM_EXITMENULOOP),
+                             ENTRY(WM_NEXTMENU),
+                             ENTRY(WM_SIZING),
+                             ENTRY(WM_CAPTURECHANGED),
+                             ENTRY(WM_MOVING),
+                             ENTRY(WM_POWERBROADCAST),
+                             ENTRY(WM_DEVICECHANGE),
+                             ENTRY(WM_MDICREATE),
+                             ENTRY(WM_MDIDESTROY),
+                             ENTRY(WM_MDIACTIVATE),
+                             ENTRY(WM_MDIRESTORE),
+                             ENTRY(WM_MDINEXT),
+                             ENTRY(WM_MDIMAXIMIZE),
+                             ENTRY(WM_MDITILE),
+                             ENTRY(WM_MDICASCADE),
+                             ENTRY(WM_MDIICONARRANGE),
+                             ENTRY(WM_MDIGETACTIVE),
+                             ENTRY(WM_MDISETMENU),
+                             ENTRY(WM_ENTERSIZEMOVE),
+                             ENTRY(WM_EXITSIZEMOVE),
+                             ENTRY(WM_DROPFILES),
+                             ENTRY(WM_MDIREFRESHMENU),
+                             ENTRY(WM_IME_SETCONTEXT),
+                             ENTRY(WM_IME_NOTIFY),
+                             ENTRY(WM_IME_CONTROL),
+                             ENTRY(WM_IME_COMPOSITIONFULL),
+                             ENTRY(WM_IME_SELECT),
+                             ENTRY(WM_IME_CHAR),
+                             ENTRY(WM_IME_REQUEST),
+                             ENTRY(WM_IME_KEYDOWN),
+                             ENTRY(WM_IME_KEYUP),
+                             ENTRY(WM_NCMOUSEHOVER),
+                             ENTRY(WM_MOUSEHOVER),
+                             ENTRY(WM_MOUSELEAVE),
+                             ENTRY(WM_CUT),
+                             ENTRY(WM_COPY),
+                             ENTRY(WM_PASTE),
+                             ENTRY(WM_CLEAR),
+                             ENTRY(WM_UNDO),
+                             ENTRY(WM_RENDERFORMAT),
+                             ENTRY(WM_RENDERALLFORMATS),
+                             ENTRY(WM_DESTROYCLIPBOARD),
+                             ENTRY(WM_DRAWCLIPBOARD),
+                             ENTRY(WM_PAINTCLIPBOARD),
+                             ENTRY(WM_VSCROLLCLIPBOARD),
+                             ENTRY(WM_SIZECLIPBOARD),
+                             ENTRY(WM_ASKCBFORMATNAME),
+                             ENTRY(WM_CHANGECBCHAIN),
+                             ENTRY(WM_HSCROLLCLIPBOARD),
+                             ENTRY(WM_QUERYNEWPALETTE),
+                             ENTRY(WM_PALETTEISCHANGING),
+                             ENTRY(WM_PALETTECHANGED),
+                             ENTRY(WM_HOTKEY),
+                             ENTRY(WM_PRINT),
+                             ENTRY(WM_PRINTCLIENT),
+                             ENTRY(WM_THEMECHANGED),
+                             ENTRY(WM_HANDHELDFIRST),
+                             ENTRY(WM_HANDHELDLAST),
+                             ENTRY(WM_AFXFIRST),
+                             ENTRY(WM_AFXLAST),
+                             ENTRY(WM_PENWINFIRST),
+                             ENTRY(WM_PENWINLAST),
+                             ENTRY(WM_APP),
+                             ENTRY(WM_DWMCOMPOSITIONCHANGED),
+                             ENTRY(WM_DWMNCRENDERINGCHANGED),
+                             ENTRY(WM_DWMCOLORIZATIONCOLORCHANGED),
+                             ENTRY(WM_DWMWINDOWMAXIMIZEDCHANGE),
+                             ENTRY(WM_DWMSENDICONICTHUMBNAIL),
+                             ENTRY(WM_DWMSENDICONICLIVEPREVIEWBITMAP),
+                             ENTRY(WM_TABLET_QUERYSYSTEMGESTURESTATUS),
+                             ENTRY(WM_GESTURE),
+                             ENTRY(WM_GESTURENOTIFY),
+                             ENTRY(WM_GETTITLEBARINFOEX),
+                             {nullptr, 0x0}};
+#undef ENTRY
+
+#ifdef MOZ_PLACES
+NS_IMPL_ISUPPORTS(myDownloadObserver, nsIDownloadObserver)
+NS_IMPL_ISUPPORTS(AsyncFaviconDataReady, nsIFaviconDataCallback)
+#endif
+NS_IMPL_ISUPPORTS(AsyncEncodeAndWriteIcon, nsIRunnable)
+NS_IMPL_ISUPPORTS(AsyncDeleteAllFaviconsFromDisk, nsIRunnable)
+
+const char FaviconHelper::kJumpListCacheDir[] = "jumpListCache";
+const char FaviconHelper::kShortcutCacheDir[] = "shortcutCache";
+
+// Prefix for path used by NT calls.
+const wchar_t kNTPrefix[] = L"\\??\\";
+const size_t kNTPrefixLen = ArrayLength(kNTPrefix) - 1;
+
+struct CoTaskMemFreePolicy {
+  void operator()(void* aPtr) { ::CoTaskMemFree(aPtr); }
+};
+
+SetThreadDpiAwarenessContextProc WinUtils::sSetThreadDpiAwarenessContext = NULL;
+EnableNonClientDpiScalingProc WinUtils::sEnableNonClientDpiScaling = NULL;
+GetSystemMetricsForDpiProc WinUtils::sGetSystemMetricsForDpi = NULL;
+
+/* static */
+void WinUtils::Initialize() {
+  if (IsWin10OrLater()) {
+    HMODULE user32Dll = ::GetModuleHandleW(L"user32");
+    if (user32Dll) {
+      auto getThreadDpiAwarenessContext =
+          (decltype(GetThreadDpiAwarenessContext)*)::GetProcAddress(
+              user32Dll, "GetThreadDpiAwarenessContext");
+      auto areDpiAwarenessContextsEqual =
+          (decltype(AreDpiAwarenessContextsEqual)*)::GetProcAddress(
+              user32Dll, "AreDpiAwarenessContextsEqual");
+      if (getThreadDpiAwarenessContext && areDpiAwarenessContextsEqual &&
+          areDpiAwarenessContextsEqual(
+              getThreadDpiAwarenessContext(),
+              DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE)) {
+        // Only per-monitor v1 requires these workarounds.
+        sEnableNonClientDpiScaling =
+            (EnableNonClientDpiScalingProc)::GetProcAddress(
+                user32Dll, "EnableNonClientDpiScaling");
+        sSetThreadDpiAwarenessContext =
+            (SetThreadDpiAwarenessContextProc)::GetProcAddress(
+                user32Dll, "SetThreadDpiAwarenessContext");
+      }
+
+      sGetSystemMetricsForDpi = (GetSystemMetricsForDpiProc)::GetProcAddress(
+          user32Dll, "GetSystemMetricsForDpi");
+    }
+  }
+}
+
+// static
+LRESULT WINAPI WinUtils::NonClientDpiScalingDefWindowProcW(HWND hWnd, UINT msg,
+                                                           WPARAM wParam,
+                                                           LPARAM lParam) {
+  // NOTE: this function was copied out into the body of the pre-XUL skeleton
+  // UI window proc (PreXULSkeletonUI.cpp). If this function changes at any
+  // point, we should probably factor this out and use it from both locations.
+  if (msg == WM_NCCREATE && sEnableNonClientDpiScaling) {
+    sEnableNonClientDpiScaling(hWnd);
+  }
+  return ::DefWindowProcW(hWnd, msg, wParam, lParam);
+}
+
+// static
+void WinUtils::LogW(const wchar_t* fmt, ...) {
+  va_list args = nullptr;
+  if (!lstrlenW(fmt)) {
+    return;
+  }
+  va_start(args, fmt);
+  int buflen = _vscwprintf(fmt, args);
+  wchar_t* buffer = new wchar_t[buflen + 1];
+  if (!buffer) {
+    va_end(args);
+    return;
+  }
+  vswprintf(buffer, buflen, fmt, args);
+  va_end(args);
+
+  // MSVC, including remote debug sessions
+  OutputDebugStringW(buffer);
+  OutputDebugStringW(L"\n");
+
+  int len =
+      WideCharToMultiByte(CP_ACP, 0, buffer, -1, nullptr, 0, nullptr, nullptr);
+  if (len) {
+    char* utf8 = new char[len];
+    if (WideCharToMultiByte(CP_ACP, 0, buffer, -1, utf8, len, nullptr,
+                            nullptr) > 0) {
+      // desktop console
+      printf("%s\n", utf8);
+      NS_ASSERTION(gWindowsLog,
+                   "Called WinUtils Log() but Widget "
+                   "log module doesn't exist!");
+      MOZ_LOG(gWindowsLog, LogLevel::Error, (utf8));
+    }
+    delete[] utf8;
+  }
+  delete[] buffer;
+}
+
+// static
+void WinUtils::Log(const char* fmt, ...) {
+  va_list args = nullptr;
+  if (!strlen(fmt)) {
+    return;
+  }
+  va_start(args, fmt);
+  int buflen = _vscprintf(fmt, args);
+  char* buffer = new char[buflen + 1];
+  if (!buffer) {
+    va_end(args);
+    return;
+  }
+  vsprintf(buffer, fmt, args);
+  va_end(args);
+
+  // MSVC, including remote debug sessions
+  OutputDebugStringA(buffer);
+  OutputDebugStringW(L"\n");
+
+  // desktop console
+  printf("%s\n", buffer);
+
+  NS_ASSERTION(gWindowsLog,
+               "Called WinUtils Log() but Widget "
+               "log module doesn't exist!");
+  MOZ_LOG(gWindowsLog, LogLevel::Error, (buffer));
+  delete[] buffer;
+}
+
+// static
+float WinUtils::SystemDPI() {
+  if (XRE_IsContentProcess()) {
+    return WinContentSystemParameters::GetSingleton()->SystemDPI();
+  }
+  // The result of GetDeviceCaps won't change dynamically, as it predates
+  // per-monitor DPI and support for on-the-fly resolution changes.
+  // Therefore, we only need to look it up once.
+  static float dpi = 0;
+  if (dpi <= 0) {
+    HDC screenDC = GetDC(nullptr);
+    dpi = GetDeviceCaps(screenDC, LOGPIXELSY);
+    ReleaseDC(nullptr, screenDC);
+  }
+
+  // Bug 1012487 - dpi can be 0 when the Screen DC is used off the
+  // main thread on windows. For now just assume a 100% DPI for this
+  // drawing call.
+  // XXX - fixme!
+  return dpi > 0 ? dpi : 96;
+}
+
+// static
+double WinUtils::SystemScaleFactor() { return SystemDPI() / 96.0; }
+
+#if WINVER < 0x603
+typedef enum {
+  MDT_EFFECTIVE_DPI = 0,
+  MDT_ANGULAR_DPI = 1,
+  MDT_RAW_DPI = 2,
+  MDT_DEFAULT = MDT_EFFECTIVE_DPI
+} MONITOR_DPI_TYPE;
+
+typedef enum {
+  PROCESS_DPI_UNAWARE = 0,
+  PROCESS_SYSTEM_DPI_AWARE = 1,
+  PROCESS_PER_MONITOR_DPI_AWARE = 2
+} PROCESS_DPI_AWARENESS;
+#endif
+
+typedef HRESULT(WINAPI* GETDPIFORMONITORPROC)(HMONITOR, MONITOR_DPI_TYPE, UINT*,
+                                              UINT*);
+
+typedef HRESULT(WINAPI* GETPROCESSDPIAWARENESSPROC)(HANDLE,
+                                                    PROCESS_DPI_AWARENESS*);
+
+GETDPIFORMONITORPROC sGetDpiForMonitor;
+GETPROCESSDPIAWARENESSPROC sGetProcessDpiAwareness;
+
+static bool SlowIsPerMonitorDPIAware() {
+  // Intentionally leak the handle.
+  HMODULE shcore = LoadLibraryEx(L"shcore", NULL, LOAD_LIBRARY_SEARCH_SYSTEM32);
+  if (shcore) {
+    sGetDpiForMonitor =
+        (GETDPIFORMONITORPROC)GetProcAddress(shcore, "GetDpiForMonitor");
+    sGetProcessDpiAwareness = (GETPROCESSDPIAWARENESSPROC)GetProcAddress(
+        shcore, "GetProcessDpiAwareness");
+  }
+  PROCESS_DPI_AWARENESS dpiAwareness;
+  return sGetDpiForMonitor && sGetProcessDpiAwareness &&
+         SUCCEEDED(
+             sGetProcessDpiAwareness(GetCurrentProcess(), &dpiAwareness)) &&
+         dpiAwareness == PROCESS_PER_MONITOR_DPI_AWARE;
+}
+
+/* static */
+bool WinUtils::IsPerMonitorDPIAware() {
+  if (XRE_IsContentProcess()) {
+    return WinContentSystemParameters::GetSingleton()->IsPerMonitorDPIAware();
+  }
+  static bool perMonitorDPIAware = SlowIsPerMonitorDPIAware();
+  return perMonitorDPIAware;
+}
+
+/* static */
+float WinUtils::MonitorDPI(HMONITOR aMonitor) {
+  if (IsPerMonitorDPIAware()) {
+    UINT dpiX, dpiY = 96;
+    sGetDpiForMonitor(aMonitor ? aMonitor : GetPrimaryMonitor(),
+                      MDT_EFFECTIVE_DPI, &dpiX, &dpiY);
+    return dpiY;
+  }
+
+  // We're not per-monitor aware, use system DPI instead.
+  return SystemDPI();
+}
+
+/* static */
+double WinUtils::LogToPhysFactor(HMONITOR aMonitor) {
+  return MonitorDPI(aMonitor) / 96.0;
+}
+
+/* static */
+int32_t WinUtils::LogToPhys(HMONITOR aMonitor, double aValue) {
+  return int32_t(NS_round(aValue * LogToPhysFactor(aMonitor)));
+}
+
+/* static */
+HMONITOR
+WinUtils::GetPrimaryMonitor() {
+  const POINT pt = {0, 0};
+  return ::MonitorFromPoint(pt, MONITOR_DEFAULTTOPRIMARY);
+}
+
+/* static */
+HMONITOR
+WinUtils::MonitorFromRect(const gfx::Rect& rect) {
+  // convert coordinates from desktop to device pixels for MonitorFromRect
+  double dpiScale =
+      IsPerMonitorDPIAware() ? 1.0 : LogToPhysFactor(GetPrimaryMonitor());
+
+  RECT globalWindowBounds = {NSToIntRound(dpiScale * rect.X()),
+                             NSToIntRound(dpiScale * rect.Y()),
+                             NSToIntRound(dpiScale * (rect.XMost())),
+                             NSToIntRound(dpiScale * (rect.YMost()))};
+
+  return ::MonitorFromRect(&globalWindowBounds, MONITOR_DEFAULTTONEAREST);
+}
+
+/* static */
+bool WinUtils::HasSystemMetricsForDpi() {
+  return (sGetSystemMetricsForDpi != NULL);
+}
+
+/* static */
+int WinUtils::GetSystemMetricsForDpi(int nIndex, UINT dpi) {
+  if (HasSystemMetricsForDpi()) {
+    return sGetSystemMetricsForDpi(nIndex, dpi);
+  } else {
+    double scale = IsPerMonitorDPIAware() ? dpi / SystemDPI() : 1.0;
+    return NSToIntRound(::GetSystemMetrics(nIndex) * scale);
+  }
+}
+
+/* static */
+gfx::MarginDouble WinUtils::GetUnwriteableMarginsForDeviceInInches(HDC aHdc) {
+  if (!aHdc) {
+    return gfx::MarginDouble();
+  }
+
+  int pixelsPerInchY = ::GetDeviceCaps(aHdc, LOGPIXELSY);
+  int marginTop = ::GetDeviceCaps(aHdc, PHYSICALOFFSETY);
+  int printableAreaHeight = ::GetDeviceCaps(aHdc, VERTRES);
+  int physicalHeight = ::GetDeviceCaps(aHdc, PHYSICALHEIGHT);
+
+  double marginTopInch = double(marginTop) / pixelsPerInchY;
+
+  double printableAreaHeightInch = double(printableAreaHeight) / pixelsPerInchY;
+  double physicalHeightInch = double(physicalHeight) / pixelsPerInchY;
+  double marginBottomInch =
+      physicalHeightInch - printableAreaHeightInch - marginTopInch;
+
+  int pixelsPerInchX = ::GetDeviceCaps(aHdc, LOGPIXELSX);
+  int marginLeft = ::GetDeviceCaps(aHdc, PHYSICALOFFSETX);
+  int printableAreaWidth = ::GetDeviceCaps(aHdc, HORZRES);
+  int physicalWidth = ::GetDeviceCaps(aHdc, PHYSICALWIDTH);
+
+  double marginLeftInch = double(marginLeft) / pixelsPerInchX;
+
+  double printableAreaWidthInch = double(printableAreaWidth) / pixelsPerInchX;
+  double physicalWidthInch = double(physicalWidth) / pixelsPerInchX;
+  double marginRightInch =
+      physicalWidthInch - printableAreaWidthInch - marginLeftInch;
+
+  return gfx::MarginDouble(marginTopInch, marginRightInch, marginBottomInch,
+                           marginLeftInch);
+}
+
+#ifdef ACCESSIBILITY
+/* static */
+a11y::Accessible* WinUtils::GetRootAccessibleForHWND(HWND aHwnd) {
+  nsWindow* window = GetNSWindowPtr(aHwnd);
+  if (!window) {
+    return nullptr;
+  }
+
+  return window->GetAccessible();
+}
+#endif  // ACCESSIBILITY
+
+/* static */
+bool WinUtils::PeekMessage(LPMSG aMsg, HWND aWnd, UINT aFirstMessage,
+                           UINT aLastMessage, UINT aOption) {
+  RefPtr<ITfMessagePump> msgPump = TSFTextStore::GetMessagePump();
+  if (msgPump) {
+    BOOL ret = FALSE;
+    HRESULT hr = msgPump->PeekMessageW(aMsg, aWnd, aFirstMessage, aLastMessage,
+                                       aOption, &ret);
+    NS_ENSURE_TRUE(SUCCEEDED(hr), false);
+    return ret;
+  }
+  return ::PeekMessageW(aMsg, aWnd, aFirstMessage, aLastMessage, aOption);
+}
+
+/* static */
+bool WinUtils::GetMessage(LPMSG aMsg, HWND aWnd, UINT aFirstMessage,
+                          UINT aLastMessage) {
+  RefPtr<ITfMessagePump> msgPump = TSFTextStore::GetMessagePump();
+  if (msgPump) {
+    BOOL ret = FALSE;
+    HRESULT hr =
+        msgPump->GetMessageW(aMsg, aWnd, aFirstMessage, aLastMessage, &ret);
+    NS_ENSURE_TRUE(SUCCEEDED(hr), false);
+    return ret;
+  }
+  return ::GetMessageW(aMsg, aWnd, aFirstMessage, aLastMessage);
+}
+
+#if defined(ACCESSIBILITY)
+static DWORD GetWaitFlags() {
+  DWORD result = MWMO_INPUTAVAILABLE;
+  if (XRE_IsContentProcess()) {
+    result |= MWMO_ALERTABLE;
+  }
+  return result;
+}
+#endif
+
+/* static */
+void WinUtils::WaitForMessage(DWORD aTimeoutMs) {
+#if defined(ACCESSIBILITY)
+  static const DWORD waitFlags = GetWaitFlags();
+#else
+  const DWORD waitFlags = MWMO_INPUTAVAILABLE;
+#endif
+
+  const DWORD waitStart = ::GetTickCount();
+  DWORD elapsed = 0;
+  while (true) {
+    if (aTimeoutMs != INFINITE) {
+      elapsed = ::GetTickCount() - waitStart;
+    }
+    if (elapsed >= aTimeoutMs) {
+      break;
+    }
+    DWORD result;
+    {
+      AUTO_PROFILER_THREAD_SLEEP;
+      result = ::MsgWaitForMultipleObjectsEx(0, NULL, aTimeoutMs - elapsed,
+                                             MOZ_QS_ALLEVENT, waitFlags);
+    }
+    NS_WARNING_ASSERTION(result != WAIT_FAILED, "Wait failed");
+    if (result == WAIT_TIMEOUT) {
+      break;
+    }
+#if defined(ACCESSIBILITY)
+    if (result == WAIT_IO_COMPLETION) {
+      if (NS_IsMainThread()) {
+        // We executed an APC that would have woken up the hang monitor. Since
+        // there are no more APCs pending and we are now going to sleep again,
+        // we should notify the hang monitor.
+        mozilla::BackgroundHangMonitor().NotifyWait();
+      }
+      continue;
+    }
+#endif  // defined(ACCESSIBILITY)
+
+    // Sent messages (via SendMessage and friends) are processed differently
+    // than queued messages (via PostMessage); the destination window procedure
+    // of the sent message is called during (Get|Peek)Message. Since PeekMessage
+    // does not tell us whether it processed any sent messages, we need to query
+    // this ahead of time.
+    bool haveSentMessagesPending =
+        (HIWORD(::GetQueueStatus(QS_SENDMESSAGE)) & QS_SENDMESSAGE) != 0;
+
+    MSG msg = {0};
+    if (haveSentMessagesPending ||
+        ::PeekMessageW(&msg, nullptr, 0, 0, PM_NOREMOVE)) {
+      break;
+    }
+    // The message is intended for another thread that has been synchronized
+    // with our input queue; yield to give other threads an opportunity to
+    // process the message. This should prevent busy waiting if resumed due
+    // to another thread's message.
+    ::SwitchToThread();
+  }
+}
+
+/* static */
+bool WinUtils::GetRegistryKey(HKEY aRoot, char16ptr_t aKeyName,
+                              char16ptr_t aValueName, wchar_t* aBuffer,
+                              DWORD aBufferLength) {
+  MOZ_ASSERT(aKeyName, "The key name is NULL");
+
+  HKEY key;
+  LONG result =
+      ::RegOpenKeyExW(aRoot, aKeyName, 0, KEY_READ | KEY_WOW64_32KEY, &key);
+  if (result != ERROR_SUCCESS) {
+    result =
+        ::RegOpenKeyExW(aRoot, aKeyName, 0, KEY_READ | KEY_WOW64_64KEY, &key);
+    if (result != ERROR_SUCCESS) {
+      return false;
+    }
+  }
+
+  DWORD type;
+  result = ::RegQueryValueExW(key, aValueName, nullptr, &type, (BYTE*)aBuffer,
+                              &aBufferLength);
+  ::RegCloseKey(key);
+  if (result != ERROR_SUCCESS || (type != REG_SZ && type != REG_EXPAND_SZ)) {
+    return false;
+  }
+  if (aBuffer) {
+    aBuffer[aBufferLength / sizeof(*aBuffer) - 1] = 0;
+  }
+  return true;
+}
+
+/* static */
+bool WinUtils::HasRegistryKey(HKEY aRoot, char16ptr_t aKeyName) {
+  MOZ_ASSERT(aRoot, "aRoot must not be NULL");
+  MOZ_ASSERT(aKeyName, "aKeyName must not be NULL");
+  HKEY key;
+  LONG result =
+      ::RegOpenKeyExW(aRoot, aKeyName, 0, KEY_READ | KEY_WOW64_32KEY, &key);
+  if (result != ERROR_SUCCESS) {
+    result =
+        ::RegOpenKeyExW(aRoot, aKeyName, 0, KEY_READ | KEY_WOW64_64KEY, &key);
+    if (result != ERROR_SUCCESS) {
+      return false;
+    }
+  }
+  ::RegCloseKey(key);
+  return true;
+}
+
+/* static */
+HWND WinUtils::GetTopLevelHWND(HWND aWnd, bool aStopIfNotChild,
+                               bool aStopIfNotPopup) {
+  HWND curWnd = aWnd;
+  HWND topWnd = nullptr;
+
+  while (curWnd) {
+    topWnd = curWnd;
+
+    if (aStopIfNotChild) {
+      DWORD_PTR style = ::GetWindowLongPtrW(curWnd, GWL_STYLE);
+
+      VERIFY_WINDOW_STYLE(style);
+
+      if (!(style & WS_CHILD))  // first top-level window
+        break;
+    }
+
+    HWND upWnd = ::GetParent(curWnd);  // Parent or owner (if has no parent)
+
+    // GetParent will only return the owner if the passed in window
+    // has the WS_POPUP style.
+    if (!upWnd && !aStopIfNotPopup) {
+      upWnd = ::GetWindow(curWnd, GW_OWNER);
+    }
+    curWnd = upWnd;
+  }
+
+  return topWnd;
+}
+
+static const wchar_t* GetNSWindowPropName() {
+  static wchar_t sPropName[40] = L"";
+  if (!*sPropName) {
+    _snwprintf(sPropName, 39, L"MozillansIWidgetPtr%u",
+               ::GetCurrentProcessId());
+    sPropName[39] = '\0';
+  }
+  return sPropName;
+}
+
+/* static */
+bool WinUtils::SetNSWindowBasePtr(HWND aWnd, nsWindowBase* aWidget) {
+  if (!aWidget) {
+    ::RemovePropW(aWnd, GetNSWindowPropName());
+    return true;
+  }
+  return ::SetPropW(aWnd, GetNSWindowPropName(), (HANDLE)aWidget);
+}
+
+/* static */
+nsWindowBase* WinUtils::GetNSWindowBasePtr(HWND aWnd) {
+  return static_cast<nsWindowBase*>(::GetPropW(aWnd, GetNSWindowPropName()));
+}
+
+/* static */
+nsWindow* WinUtils::GetNSWindowPtr(HWND aWnd) {
+  return static_cast<nsWindow*>(::GetPropW(aWnd, GetNSWindowPropName()));
+}
+
+static BOOL CALLBACK AddMonitor(HMONITOR, HDC, LPRECT, LPARAM aParam) {
+  (*(int32_t*)aParam)++;
+  return TRUE;
+}
+
+/* static */
+int32_t WinUtils::GetMonitorCount() {
+  int32_t monitorCount = 0;
+  EnumDisplayMonitors(nullptr, nullptr, AddMonitor, (LPARAM)&monitorCount);
+  return monitorCount;
+}
+
+/* static */
+bool WinUtils::IsOurProcessWindow(HWND aWnd) {
+  if (!aWnd) {
+    return false;
+  }
+  DWORD processId = 0;
+  ::GetWindowThreadProcessId(aWnd, &processId);
+  return (processId == ::GetCurrentProcessId());
+}
+
+/* static */
+HWND WinUtils::FindOurProcessWindow(HWND aWnd) {
+  for (HWND wnd = ::GetParent(aWnd); wnd; wnd = ::GetParent(wnd)) {
+    if (IsOurProcessWindow(wnd)) {
+      return wnd;
+    }
+  }
+  return nullptr;
+}
+
+static bool IsPointInWindow(HWND aWnd, const POINT& aPointInScreen) {
+  RECT bounds;
+  if (!::GetWindowRect(aWnd, &bounds)) {
+    return false;
+  }
+
+  return (aPointInScreen.x >= bounds.left && aPointInScreen.x < bounds.right &&
+          aPointInScreen.y >= bounds.top && aPointInScreen.y < bounds.bottom);
+}
+
+/**
+ * FindTopmostWindowAtPoint() returns the topmost child window (topmost means
+ * forground in this context) of aWnd.
+ */
+
+static HWND FindTopmostWindowAtPoint(HWND aWnd, const POINT& aPointInScreen) {
+  if (!::IsWindowVisible(aWnd) || !IsPointInWindow(aWnd, aPointInScreen)) {
+    return nullptr;
+  }
+
+  HWND childWnd = ::GetTopWindow(aWnd);
+  while (childWnd) {
+    HWND topmostWnd = FindTopmostWindowAtPoint(childWnd, aPointInScreen);
+    if (topmostWnd) {
+      return topmostWnd;
+    }
+    childWnd = ::GetNextWindow(childWnd, GW_HWNDNEXT);
+  }
+
+  return aWnd;
+}
+
+struct FindOurWindowAtPointInfo {
+  POINT mInPointInScreen;
+  HWND mOutWnd;
+};
+
+static BOOL CALLBACK FindOurWindowAtPointCallback(HWND aWnd, LPARAM aLPARAM) {
+  if (!WinUtils::IsOurProcessWindow(aWnd)) {
+    // This isn't one of our top-level windows; continue enumerating.
+    return TRUE;
+  }
+
+  // Get the top-most child window under the point.  If there's no child
+  // window, and the point is within the top-level window, then the top-level
+  // window will be returned.  (This is the usual case.  A child window
+  // would be returned for plugins.)
+  FindOurWindowAtPointInfo* info =
+      reinterpret_cast<FindOurWindowAtPointInfo*>(aLPARAM);
+  HWND childWnd = FindTopmostWindowAtPoint(aWnd, info->mInPointInScreen);
+  if (!childWnd) {
+    // This window doesn't contain the point; continue enumerating.
+    return TRUE;
+  }
+
+  // Return the HWND and stop enumerating.
+  info->mOutWnd = childWnd;
+  return FALSE;
+}
+
+/* static */
+HWND WinUtils::FindOurWindowAtPoint(const POINT& aPointInScreen) {
+  FindOurWindowAtPointInfo info;
+  info.mInPointInScreen = aPointInScreen;
+  info.mOutWnd = nullptr;
+
+  // This will enumerate all top-level windows in order from top to bottom.
+  EnumWindows(FindOurWindowAtPointCallback, reinterpret_cast<LPARAM>(&info));
+  return info.mOutWnd;
+}
+
+/* static */
+UINT WinUtils::GetInternalMessage(UINT aNativeMessage) {
+  switch (aNativeMessage) {
+    case WM_MOUSEWHEEL:
+      return MOZ_WM_MOUSEVWHEEL;
+    case WM_MOUSEHWHEEL:
+      return MOZ_WM_MOUSEHWHEEL;
+    case WM_VSCROLL:
+      return MOZ_WM_VSCROLL;
+    case WM_HSCROLL:
+      return MOZ_WM_HSCROLL;
+    default:
+      return aNativeMessage;
+  }
+}
+
+/* static */
+UINT WinUtils::GetNativeMessage(UINT aInternalMessage) {
+  switch (aInternalMessage) {
+    case MOZ_WM_MOUSEVWHEEL:
+      return WM_MOUSEWHEEL;
+    case MOZ_WM_MOUSEHWHEEL:
+      return WM_MOUSEHWHEEL;
+    case MOZ_WM_VSCROLL:
+      return WM_VSCROLL;
+    case MOZ_WM_HSCROLL:
+      return WM_HSCROLL;
+    default:
+      return aInternalMessage;
+  }
+}
+
+/* static */
+uint16_t WinUtils::GetMouseInputSource() {
+  int32_t inputSource = dom::MouseEvent_Binding::MOZ_SOURCE_MOUSE;
+  LPARAM lParamExtraInfo = ::GetMessageExtraInfo();
+  if ((lParamExtraInfo & TABLET_INK_SIGNATURE) == TABLET_INK_CHECK) {
+    inputSource = (lParamExtraInfo & TABLET_INK_TOUCH)
+                      ? dom::MouseEvent_Binding::MOZ_SOURCE_TOUCH
+                      : dom::MouseEvent_Binding::MOZ_SOURCE_PEN;
+  }
+  return static_cast<uint16_t>(inputSource);
+}
+
+/* static */
+uint16_t WinUtils::GetMousePointerID() {
+  LPARAM lParamExtraInfo = ::GetMessageExtraInfo();
+  return lParamExtraInfo & TABLET_INK_ID_MASK;
+}
+
+/* static */
+bool WinUtils::GetIsMouseFromTouch(EventMessage aEventMessage) {
+  const uint32_t MOZ_T_I_SIGNATURE = TABLET_INK_TOUCH | TABLET_INK_SIGNATURE;
+  const uint32_t MOZ_T_I_CHECK_TCH = TABLET_INK_TOUCH | TABLET_INK_CHECK;
+  return ((aEventMessage == eMouseMove || aEventMessage == eMouseDown ||
+           aEventMessage == eMouseUp || aEventMessage == eMouseAuxClick ||
+           aEventMessage == eMouseDoubleClick) &&
+          (GetMessageExtraInfo() & MOZ_T_I_SIGNATURE) == MOZ_T_I_CHECK_TCH);
+}
+
+/* static */
+MSG WinUtils::InitMSG(UINT aMessage, WPARAM wParam, LPARAM lParam, HWND aWnd) {
+  MSG msg;
+  msg.message = aMessage;
+  msg.wParam = wParam;
+  msg.lParam = lParam;
+  msg.hwnd = aWnd;
+  return msg;
+}
+
+static BOOL WINAPI EnumFirstChild(HWND hwnd, LPARAM lParam) {
+  *((HWND*)lParam) = hwnd;
+  return FALSE;
+}
+
+/* static */
+void WinUtils::InvalidatePluginAsWorkaround(nsIWidget* aWidget,
+                                            const LayoutDeviceIntRect& aRect) {
+  aWidget->Invalidate(aRect);
+
+  // XXX - Even more evil workaround!! See bug 762948, flash's bottom
+  // level sandboxed window doesn't seem to get our invalidate. We send
+  // an invalidate to it manually. This is totally specialized for this
+  // bug, for other child window structures this will just be a more or
+  // less bogus invalidate but since that should not have any bad
+  // side-effects this will have to do for now.
+  HWND current = (HWND)aWidget->GetNativeData(NS_NATIVE_WINDOW);
+
+  RECT windowRect;
+  RECT parentRect;
+
+  ::GetWindowRect(current, &parentRect);
+
+  HWND next = current;
+  do {
+    current = next;
+    ::EnumChildWindows(current, &EnumFirstChild, (LPARAM)&next);
+    ::GetWindowRect(next, &windowRect);
+    // This is relative to the screen, adjust it to be relative to the
+    // window we're reconfiguring.
+    windowRect.left -= parentRect.left;
+    windowRect.top -= parentRect.top;
+  } while (next != current && windowRect.top == 0 && windowRect.left == 0);
+
+  if (windowRect.top == 0 && windowRect.left == 0) {
+    RECT rect;
+    rect.left = aRect.X();
+    rect.top = aRect.Y();
+    rect.right = aRect.XMost();
+    rect.bottom = aRect.YMost();
+
+    ::InvalidateRect(next, &rect, FALSE);
+  }
+}
+
+#ifdef MOZ_PLACES
+/************************************************************************
+ * Constructs as AsyncFaviconDataReady Object
+ * @param aIOThread : the thread which performs the action
+ * @param aURLShortcut : Differentiates between (false)Jumplistcache and
+ *                       (true)Shortcutcache
+ * @param aRunnable : Executed in the aIOThread when the favicon cache is
+ *                    avaiable
+ ************************************************************************/
+
+AsyncFaviconDataReady::AsyncFaviconDataReady(
+    nsIURI* aNewURI, nsCOMPtr<nsIThread>& aIOThread, const bool aURLShortcut,
+    already_AddRefed<nsIRunnable> aRunnable)
+    : mNewURI(aNewURI),
+      mIOThread(aIOThread),
+      mRunnable(aRunnable),
+      mURLShortcut(aURLShortcut) {}
+
+NS_IMETHODIMP
+myDownloadObserver::OnDownloadComplete(nsIDownloader* downloader,
+                                       nsIRequest* request, nsISupports* ctxt,
+                                       nsresult status, nsIFile* result) {
+  return NS_OK;
+}
+
+nsresult AsyncFaviconDataReady::OnFaviconDataNotAvailable(void) {
+  if (!mURLShortcut) {
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIFile> icoFile;
+  nsresult rv =
+      FaviconHelper::GetOutputIconPath(mNewURI, icoFile, mURLShortcut);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsCOMPtr<nsIURI> mozIconURI;
+  rv = NS_NewURI(getter_AddRefs(mozIconURI), "moz-icon://.html?size=32");
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  nsCOMPtr<nsIChannel> channel;
+  rv = NS_NewChannel(getter_AddRefs(channel), mozIconURI,
+                     nsContentUtils::GetSystemPrincipal(),
+                     nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_SEC_CONTEXT_IS_NULL,
+                     nsIContentPolicy::TYPE_INTERNAL_IMAGE);
+
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsCOMPtr<nsIDownloadObserver> downloadObserver = new myDownloadObserver;
+  nsCOMPtr<nsIStreamListener> listener;
+  rv = NS_NewDownloader(getter_AddRefs(listener), downloadObserver, icoFile);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  return channel->AsyncOpen(listener);
+}
+
+NS_IMETHODIMP
+AsyncFaviconDataReady::OnComplete(nsIURI* aFaviconURI, uint32_t aDataLen,
+                                  const uint8_t* aData,
+                                  const nsACString& aMimeType,
+                                  uint16_t aWidth) {
+  if (!aDataLen || !aData) {
+    if (mURLShortcut) {
+      OnFaviconDataNotAvailable();
+    }
+
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIFile> icoFile;
+  nsresult rv =
+      FaviconHelper::GetOutputIconPath(mNewURI, icoFile, mURLShortcut);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsAutoString path;
+  rv = icoFile->GetPath(path);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // Decode the image from the format it was returned to us in (probably PNG)
+  nsCOMPtr<imgIContainer> container;
+  nsCOMPtr<imgITools> imgtool = do_CreateInstance("@mozilla.org/image/tools;1");
+  rv = imgtool->DecodeImageFromBuffer(reinterpret_cast<const char*>(aData),
+                                      aDataLen, aMimeType,
+                                      getter_AddRefs(container));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  RefPtr<SourceSurface> surface = container->GetFrame(
+      imgIContainer::FRAME_FIRST,
+      imgIContainer::FLAG_SYNC_DECODE | imgIContainer::FLAG_ASYNC_NOTIFY);
+  NS_ENSURE_TRUE(surface, NS_ERROR_FAILURE);
+
+  RefPtr<DataSourceSurface> dataSurface;
+  IntSize size;
+
+  if (mURLShortcut &&
+      (surface->GetSize().width < 48 || surface->GetSize().height < 48)) {
+    // Create a 48x48 surface and paint the icon into the central rect.
+    size.width = std::max(surface->GetSize().width, 48);
+    size.height = std::max(surface->GetSize().height, 48);
+    dataSurface =
+        Factory::CreateDataSourceSurface(size, SurfaceFormat::B8G8R8A8);
+    NS_ENSURE_TRUE(dataSurface, NS_ERROR_FAILURE);
+
+    DataSourceSurface::MappedSurface map;
+    if (!dataSurface->Map(DataSourceSurface::MapType::WRITE, &map)) {
+      return NS_ERROR_FAILURE;
+    }
+
+    RefPtr<DrawTarget> dt = Factory::CreateDrawTargetForData(
+        BackendType::CAIRO, map.mData, dataSurface->GetSize(), map.mStride,
+        dataSurface->GetFormat());
+    if (!dt) {
+      gfxWarning() << "AsyncFaviconDataReady::OnComplete failed in "
+                      "CreateDrawTargetForData";
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+    dt->FillRect(Rect(0, 0, size.width, size.height),
+                 ColorPattern(ToDeviceColor(sRGBColor::OpaqueWhite())));
+    IntPoint point;
+    point.x = (size.width - surface->GetSize().width) / 2;
+    point.y = (size.height - surface->GetSize().height) / 2;
+    dt->DrawSurface(surface,
+                    Rect(point.x, point.y, surface->GetSize().width,
+                         surface->GetSize().height),
+                    Rect(Point(0, 0), Size(surface->GetSize().width,
+                                           surface->GetSize().height)));
+
+    dataSurface->Unmap();
+  } else {
+    // By using the input image surface's size, we may end up encoding
+    // to a different size than a 16x16 (or bigger for higher DPI) ICO, but
+    // Windows will resize appropriately for us. If we want to encode ourselves
+    // one day because we like our resizing better, we'd have to manually
+    // resize the image here and use GetSystemMetrics w/ SM_CXSMICON and
+    // SM_CYSMICON. We don't support resizing images asynchronously at the
+    // moment anyway so getting the DPI aware icon size won't help.
+    size.width = surface->GetSize().width;
+    size.height = surface->GetSize().height;
+    dataSurface = surface->GetDataSurface();
+    NS_ENSURE_TRUE(dataSurface, NS_ERROR_FAILURE);
+  }
+
+  // Allocate a new buffer that we own and can use out of line in
+  // another thread.
+  UniquePtr<uint8_t[]> data = SurfaceToPackedBGRA(dataSurface);
+  if (!data) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  int32_t stride = 4 * size.width;
+
+  // AsyncEncodeAndWriteIcon takes ownership of the heap allocated buffer
+  nsCOMPtr<nsIRunnable> event =
+      new AsyncEncodeAndWriteIcon(path, std::move(data), stride, size.width,
+                                  size.height, mRunnable.forget());
+  mIOThread->Dispatch(event, NS_DISPATCH_NORMAL);
+
+  return NS_OK;
+}
+#endif
+
+// Warning: AsyncEncodeAndWriteIcon assumes ownership of the aData buffer passed
+// in
+AsyncEncodeAndWriteIcon::AsyncEncodeAndWriteIcon(
+    const nsAString& aIconPath, UniquePtr<uint8_t[]> aBuffer, uint32_t aStride,
+    uint32_t aWidth, uint32_t aHeight, already_AddRefed<nsIRunnable> aRunnable)
+    : mIconPath(aIconPath),
+      mBuffer(std::move(aBuffer)),
+      mRunnable(aRunnable),
+      mStride(aStride),
+      mWidth(aWidth),
+      mHeight(aHeight) {}
+
+NS_IMETHODIMP AsyncEncodeAndWriteIcon::Run() {
+  MOZ_ASSERT(!NS_IsMainThread(), "Should not be called on the main thread.");
+
+  // Note that since we're off the main thread we can't use
+  // gfxPlatform::GetPlatform()->ScreenReferenceDrawTarget()
+  RefPtr<DataSourceSurface> surface = Factory::CreateWrappingDataSourceSurface(
+      mBuffer.get(), mStride, IntSize(mWidth, mHeight),
+      SurfaceFormat::B8G8R8A8);
+
+  FILE* file = _wfopen(mIconPath.get(), L"wb");
+  if (!file) {
+    // Maybe the directory doesn't exist; try creating it, then fopen again.
+    nsresult rv = NS_ERROR_FAILURE;
+    nsCOMPtr<nsIFile> comFile = do_CreateInstance("@mozilla.org/file/local;1");
+    if (comFile) {
+      rv = comFile->InitWithPath(mIconPath);
+      if (NS_SUCCEEDED(rv)) {
+        nsCOMPtr<nsIFile> dirPath;
+        comFile->GetParent(getter_AddRefs(dirPath));
+        if (dirPath) {
+          rv = dirPath->Create(nsIFile::DIRECTORY_TYPE, 0777);
+          if (NS_SUCCEEDED(rv) || rv == NS_ERROR_FILE_ALREADY_EXISTS) {
+            file = _wfopen(mIconPath.get(), L"wb");
+            if (!file) {
+              rv = NS_ERROR_FAILURE;
+            }
+          }
+        }
+      }
+    }
+    if (!file) {
+      return rv;
+    }
+  }
+  nsresult rv = gfxUtils::EncodeSourceSurface(surface, ImageType::ICO, u""_ns,
+                                              gfxUtils::eBinaryEncode, file);
+  fclose(file);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (mRunnable) {
+    mRunnable->Run();
+  }
+  return rv;
+}
+
+AsyncEncodeAndWriteIcon::~AsyncEncodeAndWriteIcon() {}
+
+AsyncDeleteAllFaviconsFromDisk::AsyncDeleteAllFaviconsFromDisk(
+    bool aIgnoreRecent)
+    : mIgnoreRecent(aIgnoreRecent) {
+  // We can't call FaviconHelper::GetICOCacheSecondsTimeout() on non-main
+  // threads, as it reads a pref, so cache its value here.
+  mIcoNoDeleteSeconds = FaviconHelper::GetICOCacheSecondsTimeout() + 600;
+
+  // Prepare the profile directory cache on the main thread, to ensure we wont
+  // do this on non-main threads.
+  Unused << NS_GetSpecialDirectory("ProfLDS",
+                                   getter_AddRefs(mJumpListCacheDir));
+}
+
+NS_IMETHODIMP AsyncDeleteAllFaviconsFromDisk::Run() {
+  if (!mJumpListCacheDir) {
+    return NS_ERROR_FAILURE;
+  }
+  // Construct the path of our jump list cache
+  nsresult rv = mJumpListCacheDir->AppendNative(
+      nsDependentCString(FaviconHelper::kJumpListCacheDir));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsCOMPtr<nsIDirectoryEnumerator> entries;
+  rv = mJumpListCacheDir->GetDirectoryEntries(getter_AddRefs(entries));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // Loop through each directory entry and remove all ICO files found
+  do {
+    nsCOMPtr<nsIFile> currFile;
+    if (NS_FAILED(entries->GetNextFile(getter_AddRefs(currFile))) || !currFile)
+      break;
+
+    nsAutoString path;
+    if (NS_FAILED(currFile->GetPath(path))) continue;
+
+    if (StringTail(path, 4).LowerCaseEqualsASCII(".ico")) {
+      // Check if the cached ICO file exists
+      bool exists;
+      if (NS_FAILED(currFile->Exists(&exists)) || !exists) continue;
+
+      if (mIgnoreRecent) {
+        // Check to make sure the icon wasn't just recently created.
+        // If it was created recently, don't delete it yet.
+        int64_t fileModTime = 0;
+        rv = currFile->GetLastModifiedTime(&fileModTime);
+        fileModTime /= PR_MSEC_PER_SEC;
+        // If the icon is older than the regeneration time (+ 10 min to be
+        // safe), then it's old and we can get rid of it.
+        // This code is only hit directly after a regeneration.
+        int64_t nowTime = PR_Now() / int64_t(PR_USEC_PER_SEC);
+        if (NS_FAILED(rv) || (nowTime - fileModTime) < mIcoNoDeleteSeconds) {
+          continue;
+        }
+      }
+
+      // We found an ICO file that exists, so we should remove it
+      currFile->Remove(false);
+    }
+  } while (true);
+
+  return NS_OK;
+}
+
+AsyncDeleteAllFaviconsFromDisk::~AsyncDeleteAllFaviconsFromDisk() {}
+
+/*
+ * (static) If the data is available, will return the path on disk where
+ * the favicon for page aFaviconPageURI is stored.  If the favicon does not
+ * exist, or its cache is expired, this method will kick off an async request
+ * for the icon so that next time the method is called it will be available.
+ * @param aFaviconPageURI The URI of the page to obtain
+ * @param aICOFilePath The path of the icon file
+ * @param aIOThread The thread to perform the Fetch on
+ * @param aURLShortcut to distinguish between jumplistcache(false) and
+ *                     shortcutcache(true)
+ * @param aRunnable Executed in the aIOThread when the favicon cache is
+ *                  avaiable
+ */
+nsresult FaviconHelper::ObtainCachedIconFile(
+    nsCOMPtr<nsIURI> aFaviconPageURI, nsString& aICOFilePath,
+    nsCOMPtr<nsIThread>& aIOThread, bool aURLShortcut,
+    already_AddRefed<nsIRunnable> aRunnable) {
+  nsCOMPtr<nsIRunnable> runnable = aRunnable;
+  // Obtain the ICO file path
+  nsCOMPtr<nsIFile> icoFile;
+  nsresult rv = GetOutputIconPath(aFaviconPageURI, icoFile, aURLShortcut);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // Check if the cached ICO file already exists
+  bool exists;
+  rv = icoFile->Exists(&exists);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (exists) {
+    // Obtain the file's last modification date in seconds
+    int64_t fileModTime = 0;
+    rv = icoFile->GetLastModifiedTime(&fileModTime);
+    fileModTime /= PR_MSEC_PER_SEC;
+    int32_t icoReCacheSecondsTimeout = GetICOCacheSecondsTimeout();
+    int64_t nowTime = PR_Now() / int64_t(PR_USEC_PER_SEC);
+
+    // If the last mod call failed or the icon is old then re-cache it
+    // This check is in case the favicon of a page changes
+    // the next time we try to build the jump list, the data will be available.
+    if (NS_FAILED(rv) || (nowTime - fileModTime) > icoReCacheSecondsTimeout) {
+      CacheIconFileFromFaviconURIAsync(aFaviconPageURI, icoFile, aIOThread,
+                                       aURLShortcut, runnable.forget());
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+  } else {
+    // The file does not exist yet, obtain it async from the favicon service so
+    // that the next time we try to build the jump list it'll be available.
+    CacheIconFileFromFaviconURIAsync(aFaviconPageURI, icoFile, aIOThread,
+                                     aURLShortcut, runnable.forget());
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  // The icoFile is filled with a path that exists, get its path
+  rv = icoFile->GetPath(aICOFilePath);
+  return rv;
+}
+
+nsresult FaviconHelper::HashURI(nsCOMPtr<nsICryptoHash>& aCryptoHash,
+                                nsIURI* aUri, nsACString& aUriHash) {
+  if (!aUri) return NS_ERROR_INVALID_ARG;
+
+  nsAutoCString spec;
+  nsresult rv = aUri->GetSpec(spec);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (!aCryptoHash) {
+    aCryptoHash = do_CreateInstance(NS_CRYPTO_HASH_CONTRACTID, &rv);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
+  rv = aCryptoHash->Init(nsICryptoHash::MD5);
+  NS_ENSURE_SUCCESS(rv, rv);
+  rv = aCryptoHash->Update(
+      reinterpret_cast<const uint8_t*>(spec.BeginReading()), spec.Length());
+  NS_ENSURE_SUCCESS(rv, rv);
+  rv = aCryptoHash->Finish(true, aUriHash);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  return NS_OK;
+}
+
+// (static) Obtains the ICO file for the favicon at page aFaviconPageURI
+// If successful, the file path on disk is in the format:
+// <ProfLDS>\jumpListCache\<hash(aFaviconPageURI)>.ico
+nsresult FaviconHelper::GetOutputIconPath(nsCOMPtr<nsIURI> aFaviconPageURI,
+                                          nsCOMPtr<nsIFile>& aICOFile,
+                                          bool aURLShortcut) {
+  // Hash the input URI and replace any / with _
+  nsAutoCString inputURIHash;
+  nsCOMPtr<nsICryptoHash> cryptoHash;
+  nsresult rv = HashURI(cryptoHash, aFaviconPageURI, inputURIHash);
+  NS_ENSURE_SUCCESS(rv, rv);
+  char* cur = inputURIHash.BeginWriting();
+  char* end = inputURIHash.EndWriting();
+  for (; cur < end; ++cur) {
+    if ('/' == *cur) {
+      *cur = '_';
+    }
+  }
+
+  // Obtain the local profile directory and construct the output icon file path
+  rv = NS_GetSpecialDirectory("ProfLDS", getter_AddRefs(aICOFile));
+  NS_ENSURE_SUCCESS(rv, rv);
+  if (!aURLShortcut)
+    rv = aICOFile->AppendNative(nsDependentCString(kJumpListCacheDir));
+  else
+    rv = aICOFile->AppendNative(nsDependentCString(kShortcutCacheDir));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // Append the icon extension
+  inputURIHash.AppendLiteral(".ico");
+  rv = aICOFile->AppendNative(inputURIHash);
+
+  return rv;
+}
+
+// (static) Asynchronously creates a cached ICO file on disk for the favicon of
+// page aFaviconPageURI and stores it to disk at the path of aICOFile.
+nsresult FaviconHelper::CacheIconFileFromFaviconURIAsync(
+    nsCOMPtr<nsIURI> aFaviconPageURI, nsCOMPtr<nsIFile> aICOFile,
+    nsCOMPtr<nsIThread>& aIOThread, bool aURLShortcut,
+    already_AddRefed<nsIRunnable> aRunnable) {
+  nsCOMPtr<nsIRunnable> runnable = aRunnable;
+#ifdef MOZ_PLACES
+  // Obtain the favicon service and get the favicon for the specified page
+  nsCOMPtr<nsIFaviconService> favIconSvc(
+      do_GetService("@mozilla.org/browser/favicon-service;1"));
+  NS_ENSURE_TRUE(favIconSvc, NS_ERROR_FAILURE);
+
+  nsCOMPtr<nsIFaviconDataCallback> callback =
+      new mozilla::widget::AsyncFaviconDataReady(
+          aFaviconPageURI, aIOThread, aURLShortcut, runnable.forget());
+
+  favIconSvc->GetFaviconDataForPage(aFaviconPageURI, callback, 0);
+#endif
+  return NS_OK;
+}
+
+// Obtains the jump list 'ICO cache timeout in seconds' pref
+int32_t FaviconHelper::GetICOCacheSecondsTimeout() {
+  // Only obtain the setting at most once from the pref service.
+  // In the rare case that 2 threads call this at the same
+  // time it is no harm and we will simply obtain the pref twice.
+  // None of the taskbar list prefs are currently updated via a
+  // pref observer so I think this should suffice.
+  const int32_t kSecondsPerDay = 86400;
+  static bool alreadyObtained = false;
+  static int32_t icoReCacheSecondsTimeout = kSecondsPerDay;
+  if (alreadyObtained) {
+    return icoReCacheSecondsTimeout;
+  }
+
+  // Obtain the pref
+  const char PREF_ICOTIMEOUT[] = "browser.taskbar.lists.icoTimeoutInSeconds";
+  icoReCacheSecondsTimeout =
+      Preferences::GetInt(PREF_ICOTIMEOUT, kSecondsPerDay);
+  alreadyObtained = true;
+  return icoReCacheSecondsTimeout;
+}
+
+/* static */
+bool WinUtils::GetShellItemPath(IShellItem* aItem, nsString& aResultString) {
+  NS_ENSURE_TRUE(aItem, false);
+  LPWSTR str = nullptr;
+  if (FAILED(aItem->GetDisplayName(SIGDN_FILESYSPATH, &str))) return false;
+  aResultString.Assign(str);
+  CoTaskMemFree(str);
+  return !aResultString.IsEmpty();
+}
+
+/* static */
+LayoutDeviceIntRegion WinUtils::ConvertHRGNToRegion(HRGN aRgn) {
+  NS_ASSERTION(aRgn, "Don't pass NULL region here");
+
+  LayoutDeviceIntRegion rgn;
+
+  DWORD size = ::GetRegionData(aRgn, 0, nullptr);
+  AutoTArray<uint8_t, 100> buffer;
+  buffer.SetLength(size);
+
+  RGNDATA* data = reinterpret_cast<RGNDATA*>(buffer.Elements());
+  if (!::GetRegionData(aRgn, size, data)) return rgn;
+
+  if (data->rdh.nCount > MAX_RECTS_IN_REGION) {
+    rgn = ToIntRect(data->rdh.rcBound);
+    return rgn;
+  }
+
+  RECT* rects = reinterpret_cast<RECT*>(data->Buffer);
+  for (uint32_t i = 0; i < data->rdh.nCount; ++i) {
+    RECT* r = rects + i;
+    rgn.Or(rgn, ToIntRect(*r));
+  }
+
+  return rgn;
+}
+
+LayoutDeviceIntRect WinUtils::ToIntRect(const RECT& aRect) {
+  return LayoutDeviceIntRect(aRect.left, aRect.top, aRect.right - aRect.left,
+                             aRect.bottom - aRect.top);
+}
+
+/* static */
+bool WinUtils::IsIMEEnabled(const InputContext& aInputContext) {
+  return IsIMEEnabled(aInputContext.mIMEState.mEnabled);
+}
+
+/* static */
+bool WinUtils::IsIMEEnabled(IMEEnabled aIMEState) {
+  return aIMEState == IMEEnabled::Enabled;
+}
+
+/* static */
+void WinUtils::SetupKeyModifiersSequence(nsTArray<KeyPair>* aArray,
+                                         uint32_t aModifiers, UINT aMessage) {
+  MOZ_ASSERT(!(aModifiers & nsIWidget::ALTGRAPH) ||
+             !(aModifiers & (nsIWidget::CTRL_L | nsIWidget::ALT_R)));
+  if (aMessage == WM_KEYUP) {
+    // If AltGr is released, ControlLeft key is released first, then,
+    // AltRight key is released.
+    if (aModifiers & nsIWidget::ALTGRAPH) {
+      aArray->AppendElement(
+          KeyPair(VK_CONTROL, VK_LCONTROL, ScanCode::eControlLeft));
+      aArray->AppendElement(KeyPair(VK_MENU, VK_RMENU, ScanCode::eAltRight));
+    }
+    for (uint32_t i = ArrayLength(sModifierKeyMap); i; --i) {
+      const uint32_t* map = sModifierKeyMap[i - 1];
+      if (aModifiers & map[0]) {
+        aArray->AppendElement(KeyPair(map[1], map[2], map[3]));
+      }
+    }
+  } else {
+    for (uint32_t i = 0; i < ArrayLength(sModifierKeyMap); ++i) {
+      const uint32_t* map = sModifierKeyMap[i];
+      if (aModifiers & map[0]) {
+        aArray->AppendElement(KeyPair(map[1], map[2], map[3]));
+      }
+    }
+    // If AltGr is pressed, ControlLeft key is pressed first, then,
+    // AltRight key is pressed.
+    if (aModifiers & nsIWidget::ALTGRAPH) {
+      aArray->AppendElement(
+          KeyPair(VK_CONTROL, VK_LCONTROL, ScanCode::eControlLeft));
+      aArray->AppendElement(KeyPair(VK_MENU, VK_RMENU, ScanCode::eAltRight));
+    }
+  }
+}
+
+/* static */
+nsresult WinUtils::WriteBitmap(nsIFile* aFile, imgIContainer* aImage) {
+  RefPtr<SourceSurface> surface = aImage->GetFrame(
+      imgIContainer::FRAME_FIRST,
+      imgIContainer::FLAG_SYNC_DECODE | imgIContainer::FLAG_ASYNC_NOTIFY);
+  NS_ENSURE_TRUE(surface, NS_ERROR_FAILURE);
+
+  return WriteBitmap(aFile, surface);
+}
+
+/* static */
+nsresult WinUtils::WriteBitmap(nsIFile* aFile, SourceSurface* surface) {
+  nsresult rv;
+
+  // For either of the following formats we want to set the biBitCount member
+  // of the BITMAPINFOHEADER struct to 32, below. For that value the bitmap
+  // format defines that the A8/X8 WORDs in the bitmap byte stream be ignored
+  // for the BI_RGB value we use for the biCompression member.
+  MOZ_ASSERT(surface->GetFormat() == SurfaceFormat::B8G8R8A8 ||
+             surface->GetFormat() == SurfaceFormat::B8G8R8X8);
+
+  RefPtr<DataSourceSurface> dataSurface = surface->GetDataSurface();
+  NS_ENSURE_TRUE(dataSurface, NS_ERROR_FAILURE);
+
+  int32_t width = dataSurface->GetSize().width;
+  int32_t height = dataSurface->GetSize().height;
+  int32_t bytesPerPixel = 4 * sizeof(uint8_t);
+  uint32_t bytesPerRow = bytesPerPixel * width;
+  bool hasAlpha = surface->GetFormat() == SurfaceFormat::B8G8R8A8;
+
+  // initialize these bitmap structs which we will later
+  // serialize directly to the head of the bitmap file
+  BITMAPV4HEADER bmi;
+  memset(&bmi, 0, sizeof(BITMAPV4HEADER));
+  bmi.bV4Size = sizeof(BITMAPV4HEADER);
+  bmi.bV4Width = width;
+  bmi.bV4Height = height;
+  bmi.bV4Planes = 1;
+  bmi.bV4BitCount = (WORD)bytesPerPixel * 8;
+  bmi.bV4V4Compression = hasAlpha ? BI_BITFIELDS : BI_RGB;
+  bmi.bV4SizeImage = bytesPerRow * height;
+  bmi.bV4CSType = LCS_sRGB;
+  if (hasAlpha) {
+    bmi.bV4RedMask = 0x00FF0000;
+    bmi.bV4GreenMask = 0x0000FF00;
+    bmi.bV4BlueMask = 0x000000FF;
+    bmi.bV4AlphaMask = 0xFF000000;
+  }
+
+  BITMAPFILEHEADER bf;
+  DWORD colormask[3];
+  bf.bfType = 0x4D42;  // 'BM'
+  bf.bfReserved1 = 0;
+  bf.bfReserved2 = 0;
+  bf.bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPV4HEADER) +
+                 (hasAlpha ? sizeof(colormask) : 0);
+  bf.bfSize = bf.bfOffBits + bmi.bV4SizeImage;
+
+  // get a file output stream
+  nsCOMPtr<nsIOutputStream> stream;
+  rv = NS_NewLocalFileOutputStream(getter_AddRefs(stream), aFile);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  DataSourceSurface::MappedSurface map;
+  if (!dataSurface->Map(DataSourceSurface::MapType::READ, &map)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // write the bitmap headers and rgb pixel data to the file
+  rv = NS_ERROR_FAILURE;
+  if (stream) {
+    uint32_t written;
+    stream->Write((const char*)&bf, sizeof(BITMAPFILEHEADER), &written);
+    if (written == sizeof(BITMAPFILEHEADER)) {
+      stream->Write((const char*)&bmi, sizeof(BITMAPV4HEADER), &written);
+      if (written == sizeof(BITMAPV4HEADER)) {
+        if (hasAlpha) {
+          // color mask
+          colormask[0] = 0x00FF0000;
+          colormask[1] = 0x0000FF00;
+          colormask[2] = 0x000000FF;
+
+          stream->Write((const char*)colormask, sizeof(colormask), &written);
+        }
+        if (!hasAlpha || written == sizeof(colormask)) {
+          // write out the image data backwards because the desktop won't
+          // show bitmaps with negative heights for top-to-bottom
+          uint32_t i = map.mStride * height;
+          do {
+            i -= map.mStride;
+            stream->Write(((const char*)map.mData) + i, bytesPerRow, &written);
+            if (written == bytesPerRow) {
+              rv = NS_OK;
+            } else {
+              rv = NS_ERROR_FAILURE;
+              break;
+            }
+          } while (i != 0);
+        }
+      }
+    }
+
+    stream->Close();
+  }
+
+  dataSurface->Unmap();
+
+  return rv;
+}
+
+// This is in use here and in dom/events/TouchEvent.cpp
+/* static */
+uint32_t WinUtils::IsTouchDeviceSupportPresent() {
+  int32_t touchCapabilities = ::GetSystemMetrics(SM_DIGITIZER);
+  return (touchCapabilities & NID_READY) &&
+         (touchCapabilities & (NID_EXTERNAL_TOUCH | NID_INTEGRATED_TOUCH));
+}
+
+/* static */
+uint32_t WinUtils::GetMaxTouchPoints() {
+  if (IsTouchDeviceSupportPresent()) {
+    return GetSystemMetrics(SM_MAXIMUMTOUCHES);
+  }
+  return 0;
+}
+
+/* static */
+POWER_PLATFORM_ROLE
+WinUtils::GetPowerPlatformRole() {
+  typedef POWER_PLATFORM_ROLE(WINAPI *
+                              PowerDeterminePlatformRoleEx)(ULONG Version);
+  static PowerDeterminePlatformRoleEx power_determine_platform_role =
+      reinterpret_cast<PowerDeterminePlatformRoleEx>(::GetProcAddress(
+          ::LoadLibraryW(L"PowrProf.dll"), "PowerDeterminePlatformRoleEx"));
+
+  POWER_PLATFORM_ROLE powerPlatformRole = PlatformRoleUnspecified;
+  if (!power_determine_platform_role) {
+    return powerPlatformRole;
+  }
+
+  return power_determine_platform_role(POWER_PLATFORM_ROLE_V2);
+}
+
+static bool IsWindows10TabletMode() {
+  nsCOMPtr<nsIWindowsUIUtils> uiUtils(
+      do_GetService("@mozilla.org/windows-ui-utils;1"));
+  if (NS_WARN_IF(!uiUtils)) {
+    return false;
+  }
+  bool isInTabletMode = false;
+  uiUtils->GetInTabletMode(&isInTabletMode);
+  return isInTabletMode;
+}
+
+static bool CallGetAutoRotationState(AR_STATE* aRotationState) {
+  typedef BOOL(WINAPI * GetAutoRotationStateFunc)(PAR_STATE pState);
+  static GetAutoRotationStateFunc get_auto_rotation_state_func =
+      reinterpret_cast<GetAutoRotationStateFunc>(::GetProcAddress(
+          GetModuleHandleW(L"user32.dll"), "GetAutoRotationState"));
+  if (get_auto_rotation_state_func) {
+    ZeroMemory(aRotationState, sizeof(AR_STATE));
+    return get_auto_rotation_state_func(aRotationState);
+  }
+  return false;
+}
+
+static bool IsTabletDevice() {
+  // Guarantees that:
+  // - The device has a touch screen.
+  // - It is used as a tablet which means that it has no keyboard connected.
+  // On Windows 10 it means that it is verifying with ConvertibleSlateMode.
+
+  if (!IsWin8OrLater()) {
+    return false;
+  }
+
+  if (IsWindows10TabletMode()) {
+    return true;
+  }
+
+  if (!GetSystemMetrics(SM_MAXIMUMTOUCHES)) {
+    return false;
+  }
+
+  // If the device is docked, the user is treating the device as a PC.
+  if (GetSystemMetrics(SM_SYSTEMDOCKED)) {
+    return false;
+  }
+
+  // If the device is not supporting rotation, it's unlikely to be a tablet,
+  // a convertible or a detachable. See:
+  // https://msdn.microsoft.com/en-us/library/windows/desktop/dn629263(v=vs.85).aspx
+  AR_STATE rotation_state;
+  if (CallGetAutoRotationState(&rotation_state) &&
+      (rotation_state & (AR_NOT_SUPPORTED | AR_LAPTOP | AR_NOSENSOR))) {
+    return false;
+  }
+
+  // PlatformRoleSlate was added in Windows 8+.
+  POWER_PLATFORM_ROLE role = WinUtils::GetPowerPlatformRole();
+  if (role == PlatformRoleMobile || role == PlatformRoleSlate) {
+    return !GetSystemMetrics(SM_CONVERTIBLESLATEMODE);
+  }
+  return false;
+}
+
+static bool IsMousePresent() {
+  if (!::GetSystemMetrics(SM_MOUSEPRESENT)) {
+    return false;
+  }
+
+  DWORD count = InputDeviceUtils::CountMouseDevices();
+  if (!count) {
+    return false;
+  }
+
+  // If there is a mouse device and if this machine is a tablet or has a
+  // digitizer, that's counted as the mouse device.
+  // FIXME: Bug 1495938:  We should drop this heuristic way once we find out a
+  // reliable way to tell there is no mouse or not.
+  if (count == 1 &&
+      (WinUtils::IsTouchDeviceSupportPresent() || IsTabletDevice())) {
+    return false;
+  }
+
+  return true;
+}
+
+/* static */
+PointerCapabilities WinUtils::GetPrimaryPointerCapabilities() {
+  if (IsTabletDevice()) {
+    return PointerCapabilities::Coarse;
+  }
+
+  if (IsMousePresent()) {
+    return PointerCapabilities::Fine | PointerCapabilities::Hover;
+  }
+
+  if (IsTouchDeviceSupportPresent()) {
+    return PointerCapabilities::Coarse;
+  }
+
+  return PointerCapabilities::None;
+}
+
+/* static */
+PointerCapabilities WinUtils::GetAllPointerCapabilities() {
+  PointerCapabilities result = PointerCapabilities::None;
+
+  if (IsTabletDevice() || IsTouchDeviceSupportPresent()) {
+    result |= PointerCapabilities::Coarse;
+  }
+
+  if (IsMousePresent()) {
+    result |= PointerCapabilities::Fine | PointerCapabilities::Hover;
+  }
+
+  return result;
+}
+
+/* static */
+bool WinUtils::ResolveJunctionPointsAndSymLinks(std::wstring& aPath) {
+  LOG_D("ResolveJunctionPointsAndSymLinks: Resolving path: %S", aPath.c_str());
+
+  wchar_t path[MAX_PATH] = {0};
+
+  nsAutoHandle handle(::CreateFileW(
+      aPath.c_str(), 0, FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
+      nullptr, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, nullptr));
+
+  if (handle == INVALID_HANDLE_VALUE) {
+    LOG_E("Failed to open file handle to resolve path. GetLastError=%d",
+          GetLastError());
+    return false;
+  }
+
+  DWORD pathLen = GetFinalPathNameByHandleW(
+      handle, path, MAX_PATH, FILE_NAME_NORMALIZED | VOLUME_NAME_DOS);
+  if (pathLen == 0 || pathLen >= MAX_PATH) {
+    LOG_E("GetFinalPathNameByHandleW failed. GetLastError=%d", GetLastError());
+    return false;
+  }
+  aPath = path;
+
+  // GetFinalPathNameByHandle sticks a '\\?\' in front of the path,
+  // but that confuses some APIs so strip it off. It will also put
+  // '\\?\UNC\' in front of network paths, we convert that to '\\'.
+  if (aPath.compare(0, 7, L"\\\\?\\UNC") == 0) {
+    aPath.erase(2, 6);
+  } else if (aPath.compare(0, 4, L"\\\\?\\") == 0) {
+    aPath.erase(0, 4);
+  }
+
+  LOG_D("ResolveJunctionPointsAndSymLinks: Resolved path to: %S",
+        aPath.c_str());
+  return true;
+}
+
+/* static */
+bool WinUtils::ResolveJunctionPointsAndSymLinks(nsIFile* aPath) {
+  MOZ_ASSERT(aPath);
+
+  nsAutoString filePath;
+  nsresult rv = aPath->GetPath(filePath);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return false;
+  }
+
+  std::wstring resolvedPath(filePath.get());
+  if (!ResolveJunctionPointsAndSymLinks(resolvedPath)) {
+    return false;
+  }
+
+  rv = aPath->InitWithPath(nsDependentString(resolvedPath.c_str()));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return false;
+  }
+
+  return true;
+}
+
+/* static */
+bool WinUtils::RunningFromANetworkDrive() {
+  wchar_t exePath[MAX_PATH];
+  if (!::GetModuleFileNameW(nullptr, exePath, MAX_PATH)) {
+    return false;
+  }
+
+  std::wstring exeString(exePath);
+  if (!widget::WinUtils::ResolveJunctionPointsAndSymLinks(exeString)) {
+    return false;
+  }
+
+  wchar_t volPath[MAX_PATH];
+  if (!::GetVolumePathNameW(exeString.c_str(), volPath, MAX_PATH)) {
+    return false;
+  }
+
+  return (::GetDriveTypeW(volPath) == DRIVE_REMOTE);
+}
+
+/* static */
+bool WinUtils::GetModuleFullPath(HMODULE aModuleHandle, nsAString& aPath) {
+  size_t bufferSize = MAX_PATH;
+  size_t len = 0;
+  while (true) {
+    aPath.SetLength(bufferSize);
+    len = (size_t)::GetModuleFileNameW(
+        aModuleHandle, (char16ptr_t)aPath.BeginWriting(), bufferSize);
+    if (!len) {
+      return false;
+    }
+    if (len == bufferSize && ::GetLastError() == ERROR_INSUFFICIENT_BUFFER) {
+      bufferSize *= 2;
+      continue;
+    }
+    aPath.Truncate(len);
+    break;
+  }
+  return true;
+}
+
+/* static */
+bool WinUtils::CanonicalizePath(nsAString& aPath) {
+  wchar_t tempPath[MAX_PATH + 1];
+  if (!PathCanonicalizeW(tempPath,
+                         (char16ptr_t)PromiseFlatString(aPath).get())) {
+    return false;
+  }
+  aPath = tempPath;
+  MOZ_ASSERT(aPath.Length() <= MAX_PATH);
+  return true;
+}
+
+/* static */
+bool WinUtils::MakeLongPath(nsAString& aPath) {
+  wchar_t tempPath[MAX_PATH + 1];
+  DWORD longResult =
+      GetLongPathNameW((char16ptr_t)PromiseFlatString(aPath).get(), tempPath,
+                       ArrayLength(tempPath));
+  if (longResult > ArrayLength(tempPath)) {
+    // Our buffer is too short, and we're guaranteeing <= MAX_PATH results.
+    return false;
+  } else if (longResult) {
+    // Success.
+    aPath = tempPath;
+    MOZ_ASSERT(aPath.Length() <= MAX_PATH);
+  }
+  // GetLongPathNameW returns 0 if the path is not found or is not rooted,
+  // but we shouldn't consider that a failure condition.
+  return true;
+}
+
+/* static */
+bool WinUtils::UnexpandEnvVars(nsAString& aPath) {
+  wchar_t tempPath[MAX_PATH + 1];
+  // PathUnExpandEnvStringsW returns false if it doesn't make any
+  // substitutions. Silently continue using the unaltered path.
+  if (PathUnExpandEnvStringsW((char16ptr_t)PromiseFlatString(aPath).get(),
+                              tempPath, ArrayLength(tempPath))) {
+    aPath = tempPath;
+    MOZ_ASSERT(aPath.Length() <= MAX_PATH);
+  }
+  return true;
+}
+
+/* static */
+WinUtils::WhitelistVec WinUtils::BuildWhitelist() {
+  WhitelistVec result;
+
+  Unused << result.emplaceBack(
+      std::make_pair(nsString(u"%ProgramFiles%"_ns), nsDependentString()));
+
+  // When no substitution is required, set the void flag
+  result.back().second.SetIsVoid(true);
+
+  Unused << result.emplaceBack(
+      std::make_pair(nsString(u"%SystemRoot%"_ns), nsDependentString()));
+  result.back().second.SetIsVoid(true);
+
+  wchar_t tmpPath[MAX_PATH + 1] = {};
+  if (GetTempPath(MAX_PATH, tmpPath)) {
+    // GetTempPath's result always ends with a backslash, which we don't want
+    uint32_t tmpPathLen = wcslen(tmpPath);
+    if (tmpPathLen) {
+      tmpPath[tmpPathLen - 1] = 0;
+    }
+
+    nsAutoString cleanTmpPath(tmpPath);
+    if (UnexpandEnvVars(cleanTmpPath)) {
+      constexpr auto tempVar = u"%TEMP%"_ns;
+      Unused << result.emplaceBack(std::make_pair(
+          nsString(cleanTmpPath), nsDependentString(tempVar, 0)));
+    }
+  }
+
+  // If we add more items to the whitelist, ensure we still don't invoke an
+  // unnecessary heap allocation.
+  MOZ_ASSERT(result.length() <= kMaxWhitelistedItems);
+
+  return result;
+}
+
+/**
+ * This function provides an array of (system path, substitution) pairs that are
+ * considered to be acceptable with respect to privacy, for the purposes of
+ * submitting within telemetry or crash reports.
+ *
+ * The substitution string's void flag may be set. If it is, no subsitution is
+ * necessary. Otherwise, the consumer should replace the system path with the
+ * substitution.
+ *
+ * @see PreparePathForTelemetry for an example of its usage.
+ */
+/* static */
+const WinUtils::WhitelistVec& WinUtils::GetWhitelistedPaths() {
+  static WhitelistVec sWhitelist([]() -> WhitelistVec {
+    auto setClearFn = [ptr = &sWhitelist]() -> void {
+      RunOnShutdown([ptr]() -> void { ptr->clear(); },
+                    ShutdownPhase::ShutdownFinal);
+    };
+
+    if (NS_IsMainThread()) {
+      setClearFn();
+    } else {
+      SchedulerGroup::Dispatch(
+          TaskCategory::Other,
+          NS_NewRunnableFunction("WinUtils::GetWhitelistedPaths",
+                                 std::move(setClearFn)));
+    }
+
+    return BuildWhitelist();
+  }());
+  return sWhitelist;
+}
+
+/**
+ * This function is located here (as opposed to nsSystemInfo or elsewhere)
+ * because we need to gather this information as early as possible during
+ * startup.
+ */
+/* static */
+bool WinUtils::GetAppInitDLLs(nsAString& aOutput) {
+  aOutput.Truncate();
+  HKEY hkey = NULL;
+  if (RegOpenKeyExW(HKEY_LOCAL_MACHINE,
+                    L"SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Windows",
+                    0, KEY_QUERY_VALUE, &hkey)) {
+    return false;
+  }
+  nsAutoRegKey key(hkey);
+  LONG status;
+  const wchar_t kLoadAppInitDLLs[] = L"LoadAppInit_DLLs";
+  DWORD loadAppInitDLLs = 0;
+  DWORD loadAppInitDLLsLen = sizeof(loadAppInitDLLs);
+  status = RegQueryValueExW(hkey, kLoadAppInitDLLs, nullptr, nullptr,
+                            (LPBYTE)&loadAppInitDLLs, &loadAppInitDLLsLen);
+  if (status != ERROR_SUCCESS) {
+    return false;
+  }
+  if (!loadAppInitDLLs) {
+    // If loadAppInitDLLs is zero then AppInit_DLLs is disabled.
+    // In this case we'll return true along with an empty output string.
+    return true;
+  }
+  DWORD numBytes = 0;
+  const wchar_t kAppInitDLLs[] = L"AppInit_DLLs";
+  // Query for required buffer size
+  status = RegQueryValueExW(hkey, kAppInitDLLs, nullptr, nullptr, nullptr,
+                            &numBytes);
+  if (status != ERROR_SUCCESS) {
+    return false;
+  }
+  // Allocate the buffer and query for the actual data
+  mozilla::UniquePtr<wchar_t[]> data =
+      mozilla::MakeUnique<wchar_t[]>(numBytes / sizeof(wchar_t));
+  status = RegQueryValueExW(hkey, kAppInitDLLs, nullptr, nullptr,
+                            (LPBYTE)data.get(), &numBytes);
+  if (status != ERROR_SUCCESS) {
+    return false;
+  }
+  // For each token, split up the filename components and then check the
+  // name of the file.
+  const wchar_t kDelimiters[] = L", ";
+  wchar_t* tokenContext = nullptr;
+  wchar_t* token = wcstok_s(data.get(), kDelimiters, &tokenContext);
+  while (token) {
+    nsAutoString cleanPath(token);
+    // Since these paths are short paths originating from the registry, we need
+    // to canonicalize them, lengthen them, and sanitize them before we can
+    // check them against the whitelist
+    if (PreparePathForTelemetry(cleanPath)) {
+      if (!aOutput.IsEmpty()) {
+        aOutput += L";";
+      }
+      aOutput += cleanPath;
+    }
+    token = wcstok_s(nullptr, kDelimiters, &tokenContext);
+  }
+  return true;
+}
+
+/* static */
+bool WinUtils::PreparePathForTelemetry(nsAString& aPath,
+                                       PathTransformFlags aFlags) {
+  if (aFlags & PathTransformFlags::Canonicalize) {
+    if (!CanonicalizePath(aPath)) {
+      return false;
+    }
+  }
+  if (aFlags & PathTransformFlags::Lengthen) {
+    if (!MakeLongPath(aPath)) {
+      return false;
+    }
+  }
+  if (aFlags & PathTransformFlags::UnexpandEnvVars) {
+    if (!UnexpandEnvVars(aPath)) {
+      return false;
+    }
+  }
+
+  const WhitelistVec& whitelistedPaths = GetWhitelistedPaths();
+
+  for (uint32_t i = 0; i < whitelistedPaths.length(); ++i) {
+    const nsString& testPath = whitelistedPaths[i].first;
+    const nsDependentString& substitution = whitelistedPaths[i].second;
+    if (StringBeginsWith(aPath, testPath, nsCaseInsensitiveStringComparator)) {
+      if (!substitution.IsVoid()) {
+        aPath.Replace(0, testPath.Length(), substitution);
+      }
+      return true;
+    }
+  }
+
+  // For non-whitelisted paths, we strip the path component and just leave
+  // the filename. We can't use nsLocalFile to do this because these paths may
+  // begin with environment variables, and nsLocalFile doesn't like
+  // non-absolute paths.
+  const nsString& flatPath = PromiseFlatString(aPath);
+  LPCWSTR leafStart = ::PathFindFileNameW(flatPath.get());
+  ptrdiff_t cutLen = leafStart - flatPath.get();
+  if (cutLen) {
+    aPath.Cut(0, cutLen);
+  } else if (aFlags & PathTransformFlags::RequireFilePath) {
+    return false;
+  }
+
+  return true;
+}
+
+}  // namespace widget
+}  // namespace mozilla