--- a/gfx/thebes/gfxGDIFontList.cpp
+++ b/gfx/thebes/gfxGDIFontList.cpp
@@ -24,17 +24,16 @@
 #include "nsAppDirectoryServiceDefs.h"
 #include "nsISimpleEnumerator.h"
 #include "nsIWindowsRegKey.h"
 #include "gfxFontConstants.h"
 #include "GeckoProfiler.h"
 
 #include "mozilla/MemoryReporting.h"
 #include "mozilla/Telemetry.h"
-#include "mozilla/WindowsVersion.h"
 
 #include <usp10.h>
 
 using namespace mozilla;
 
 #define ROUND(x) floor((x) + 0.5)
 
 #define LOG_FONTLIST(args) MOZ_LOG(gfxPlatform::GetLog(eGfxLog_fontlist), \

--- a/mfbt/WindowsVersion.h
+++ b/mfbt/WindowsVersion.h
@@ -79,91 +79,16 @@ IsWindowsBuildOrLater(uint32_t aBuild)
     minBuild = aBuild;
     return true;
   }
 
   maxBuild = aBuild;
   return false;
 }
 
-#if defined(_M_X64) || defined(_M_AMD64)
-// We support only Win7 or later on Win64.
-MOZ_ALWAYS_INLINE bool
-IsXPSP3OrLater()
-{
-  return true;
-}
-
-MOZ_ALWAYS_INLINE bool
-IsWin2003OrLater()
-{
-  return true;
-}
-
-MOZ_ALWAYS_INLINE bool
-IsWin2003SP2OrLater()
-{
-  return true;
-}
-
-MOZ_ALWAYS_INLINE bool
-IsVistaOrLater()
-{
-  return true;
-}
-
-MOZ_ALWAYS_INLINE bool
-IsVistaSP1OrLater()
-{
-  return true;
-}
-
-MOZ_ALWAYS_INLINE bool
-IsWin7OrLater()
-{
-  return true;
-}
-#else
-MOZ_ALWAYS_INLINE bool
-IsXPSP3OrLater()
-{
-  return IsWindowsVersionOrLater(0x05010300ul);
-}
-
-MOZ_ALWAYS_INLINE bool
-IsWin2003OrLater()
-{
-  return IsWindowsVersionOrLater(0x05020000ul);
-}
-
-MOZ_ALWAYS_INLINE bool
-IsWin2003SP2OrLater()
-{
-  return IsWindowsVersionOrLater(0x05020200ul);
-}
-
-MOZ_ALWAYS_INLINE bool
-IsVistaOrLater()
-{
-  return IsWindowsVersionOrLater(0x06000000ul);
-}
-
-MOZ_ALWAYS_INLINE bool
-IsVistaSP1OrLater()
-{
-  return IsWindowsVersionOrLater(0x06000100ul);
-}
-
-MOZ_ALWAYS_INLINE bool
-IsWin7OrLater()
-{
-  return IsWindowsVersionOrLater(0x06010000ul);
-}
-#endif
-
 MOZ_ALWAYS_INLINE bool
 IsWin7SP1OrLater()
 {
   return IsWindowsVersionOrLater(0x06010100ul);
 }
 
 MOZ_ALWAYS_INLINE bool
 IsWin8OrLater()
@@ -181,15 +106,14 @@ MOZ_ALWAYS_INLINE bool
 IsWin10OrLater()
 {
   return IsWindowsVersionOrLater(0x0a000000ul);
 }
 
 MOZ_ALWAYS_INLINE bool
 IsNotWin7PreRTM()
 {
-  return IsWin7SP1OrLater() || !IsWin7OrLater() ||
-         IsWindowsBuildOrLater(7600);
+  return IsWin7SP1OrLater() || IsWindowsBuildOrLater(7600);
 }
 
 } // namespace mozilla
 
 #endif /* mozilla_WindowsVersion_h */

--- a/widget/LookAndFeel.h
+++ b/widget/LookAndFeel.h
@@ -413,20 +413,17 @@ public:
     eWindowsTheme_Zune,
     eWindowsTheme_AeroLite
   };
 
   /**
    * Operating system versions.
    */
   enum OperatingSystemVersion {
-    // XXX: The XP and Vista values can now be removed (see bug 1330146).
-    eOperatingSystemVersion_WindowsXP = 0,
-    eOperatingSystemVersion_WindowsVista,
-    eOperatingSystemVersion_Windows7,
+    eOperatingSystemVersion_Windows7 = 2,
     eOperatingSystemVersion_Windows8,
     eOperatingSystemVersion_Windows10,
     eOperatingSystemVersion_Unknown
   };
 
   enum {
     eScrollArrow_None = 0,
     eScrollArrow_StartBackward = 0x1000,

--- a/widget/windows/KeyboardLayout.cpp
+++ b/widget/windows/KeyboardLayout.cpp
@@ -5,17 +5,16 @@
 
 #include "mozilla/Logging.h"
 
 #include "mozilla/ArrayUtils.h"
 #include "mozilla/DebugOnly.h"
 #include "mozilla/MouseEvents.h"
 #include "mozilla/MiscEvents.h"
 #include "mozilla/TextEvents.h"
-#include "mozilla/WindowsVersion.h"
 
 #include "nsAlgorithm.h"
 #ifdef MOZ_CRASHREPORTER
 #include "nsExceptionHandler.h"
 #endif
 #include "nsGkAtoms.h"
 #include "nsIDOMKeyEvent.h"
 #include "nsIIdleServiceInternal.h"

--- a/widget/windows/WinMessages.h
+++ b/widget/windows/WinMessages.h
@@ -40,20 +40,16 @@
 #define MOZ_WM_KEYUP                      (WM_APP+0x0319)
 #define MOZ_WM_SYSKEYDOWN                 (WM_APP+0x031A)
 #define MOZ_WM_SYSKEYUP                   (WM_APP+0x031B)
 #define MOZ_WM_CHAR                       (WM_APP+0x031C)
 #define MOZ_WM_SYSCHAR                    (WM_APP+0x031D)
 #define MOZ_WM_DEADCHAR                   (WM_APP+0x031E)
 #define MOZ_WM_SYSDEADCHAR                (WM_APP+0x031F)
 
-// Internal message for ensuring the file picker is visible on multi monitor
-// systems, and when the screen resolution changes.
-#define MOZ_WM_ENSUREVISIBLE              (WM_APP+0x374F)
-
 // XXX Should rename them to MOZ_WM_* and use safer values!
 // Messages for fullscreen transition window
 #define WM_FULLSCREEN_TRANSITION_BEFORE   (WM_USER + 0)
 #define WM_FULLSCREEN_TRANSITION_AFTER    (WM_USER + 1)
 
 /*****************************************************************************
  * WM_* messages and related constants which may not be defined by
  * old Windows SDK

--- a/widget/windows/WinMouseScrollHandler.cpp
+++ b/widget/windows/WinMouseScrollHandler.cpp
@@ -15,17 +15,16 @@
 #include "WinUtils.h"
 #include "nsGkAtoms.h"
 #include "nsIDOMWindowUtils.h"
 #include "nsIDOMWheelEvent.h"
 
 #include "mozilla/MiscEvents.h"
 #include "mozilla/MouseEvents.h"
 #include "mozilla/Preferences.h"
-#include "mozilla/WindowsVersion.h"
 
 #include <psapi.h>
 
 namespace mozilla {
 namespace widget {
 
 LazyLogModule gMouseScrollLog("MouseScrollHandlerWidgets");
 

--- a/widget/windows/WinTaskbar.cpp
+++ b/widget/windows/WinTaskbar.cpp
@@ -23,17 +23,16 @@
 #include "WinUtils.h"
 #include "TaskbarTabPreview.h"
 #include "TaskbarWindowPreview.h"
 #include "JumpListBuilder.h"
 #include "nsWidgetsCID.h"
 #include "nsPIDOMWindow.h"
 #include "nsAppDirectoryServiceDefs.h"
 #include "mozilla/Preferences.h"
-#include "mozilla/WindowsVersion.h"
 #include <io.h>
 #include <propvarutil.h>
 #include <propkey.h>
 #include <shellapi.h>
 
 const wchar_t kShellLibraryName[] =  L"shell32.dll";
 
 static NS_DEFINE_CID(kJumpListBuilderCID, NS_WIN_JUMPLISTBUILDER_CID);

--- a/widget/windows/nsDataObj.cpp
+++ b/widget/windows/nsDataObj.cpp
@@ -33,17 +33,16 @@
 #include "nsThreadUtils.h"
 #include "mozilla/Preferences.h"
 #include "nsIContentPolicy.h"
 #include "nsContentUtils.h"
 #include "nsIPrincipal.h"
 
 #include "WinUtils.h"
 #include "mozilla/LazyIdleThread.h"
-#include "mozilla/WindowsVersion.h"
 #include <algorithm>
 
 
 using namespace mozilla;
 using namespace mozilla::widget;
 
 #define DEFAULT_THREAD_TIMEOUT_MS 30000
 

--- a/widget/windows/nsFilePicker.cpp
+++ b/widget/windows/nsFilePicker.cpp
@@ -32,18 +32,16 @@ using mozilla::IsWin8OrLater;
 using mozilla::MakeUnique;
 using mozilla::mscom::EnsureMTA;
 using mozilla::UniquePtr;
 using namespace mozilla::widget;
 
 char16_t *nsFilePicker::mLastUsedUnicodeDirectory;
 char nsFilePicker::mLastUsedDirectory[MAX_PATH+1] = { 0 };
 
-static const wchar_t kDialogPtrProp[] = L"DialogPtrProperty";
-static const DWORD kDialogTimerID = 9999;
 static const unsigned long kDialogTimerTimeout = 300;
 
 #define MAX_EXTENSION_LENGTH 10
 #define FILE_BUFFER_SIZE     4096 
 
 typedef DWORD FILEOPENDIALOGOPTIONS;
 
 ///////////////////////////////////////////////////////////////////////////////