--- a/dom/media/eme/MediaKeySystemAccess.cpp
+++ b/dom/media/eme/MediaKeySystemAccess.cpp
@@ -8,17 +8,16 @@
 #include "mozilla/dom/MediaKeySystemAccessBinding.h"
 #include "mozilla/Preferences.h"
 #include "MediaPrefs.h"
 #include "nsContentTypeParser.h"
 #ifdef MOZ_FMP4
 #include "MP4Decoder.h"
 #endif
 #ifdef XP_WIN
-#include "mozilla/WindowsVersion.h"
 #include "WMFDecoderModule.h"
 #endif
 #include "nsContentCID.h"
 #include "nsServiceManagerUtils.h"
 #include "mozIGeckoMediaPluginService.h"
 #include "VideoUtils.h"
 #include "mozilla/Services.h"
 #include "nsIObserverService.h"
@@ -34,16 +33,17 @@
 #include "WebMDecoder.h"
 #include "mozilla/StaticPtr.h"
 #include "mozilla/ClearOnShutdown.h"
 #include "nsUnicharUtils.h"
 #include "mozilla/dom/MediaSource.h"
 #ifdef MOZ_WIDGET_ANDROID
 #include "FennecJNIWrappers.h"
 #endif
+
 namespace mozilla {
 namespace dom {
 
 NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(MediaKeySystemAccess,
                                       mParent)
 NS_IMPL_CYCLE_COLLECTING_ADDREF(MediaKeySystemAccess)
 NS_IMPL_CYCLE_COLLECTING_RELEASE(MediaKeySystemAccess)
 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(MediaKeySystemAccess)
@@ -135,36 +135,22 @@ MediaKeySystemAccess::GetKeySystemStatus
   }
 
   if (Preferences::GetBool("media.gmp-eme-adobe.visible", false)) {
     if (IsPrimetimeKeySystem(aKeySystem)) {
       if (!Preferences::GetBool("media.gmp-eme-adobe.enabled", false)) {
         aOutMessage = NS_LITERAL_CSTRING("Adobe EME disabled");
         return MediaKeySystemStatus::Cdm_disabled;
       }
-#ifdef XP_WIN
-      // Win Vista and later only.
-      if (!IsVistaOrLater()) {
-        aOutMessage = NS_LITERAL_CSTRING("Minimum Windows version (Vista) not met for Adobe EME");
-        return MediaKeySystemStatus::Cdm_not_supported;
-      }
-#endif
       return EnsureCDMInstalled(aKeySystem, aOutMessage);
     }
   }
 
   if (IsWidevineKeySystem(aKeySystem)) {
     if (Preferences::GetBool("media.gmp-widevinecdm.visible", false)) {
-#ifdef XP_WIN
-      // Win Vista and later only.
-      if (!IsVistaOrLater()) {
-        aOutMessage = NS_LITERAL_CSTRING("Minimum Windows version (Vista) not met for Widevine EME");
-        return MediaKeySystemStatus::Cdm_not_supported;
-      }
-#endif
       if (!Preferences::GetBool("media.gmp-widevinecdm.enabled", false)) {
         aOutMessage = NS_LITERAL_CSTRING("Widevine EME disabled");
         return MediaKeySystemStatus::Cdm_disabled;
       }
       return EnsureCDMInstalled(aKeySystem, aOutMessage);
 #ifdef MOZ_WIDGET_ANDROID
     } else if (Preferences::GetBool("media.mediadrm-widevinecdm.visible", false)) {
         nsCString keySystem = NS_ConvertUTF16toUTF8(aKeySystem);

--- a/dom/media/gmp/GMPChild.cpp
+++ b/dom/media/gmp/GMPChild.cpp
@@ -293,22 +293,20 @@ GMPChild::GetAPI(const char* aAPIName,
 
 mozilla::ipc::IPCResult
 GMPChild::RecvPreloadLibs(const nsCString& aLibs)
 {
 #ifdef XP_WIN
   // Pre-load DLLs that need to be used by the EME plugin but that can't be
   // loaded after the sandbox has started
   // Items in this must be lowercase!
-  static const char* whitelist[] = {
+  static const char *const whitelist[] = {
     "d3d9.dll", // Create an `IDirect3D9` to get adapter information
     "dxva2.dll", // Get monitor information
     "evr.dll", // MFGetStrideForBitmapInfoHeader
-    "mfh264dec.dll", // H.264 decoder (on Windows Vista)
-    "mfheaacdec.dll", // AAC decoder (on Windows Vista)
     "mfplat.dll", // MFCreateSample, MFCreateAlignedMemoryBuffer, MFCreateMediaType
     "msauddecmft.dll", // AAC decoder (on Windows 8)
     "msmpeg2adec.dll", // AAC decoder (on Windows 7)
     "msmpeg2vdec.dll", // H.264 decoder
   };
 
   nsTArray<nsCString> libs;
   SplitAt(", ", aLibs, libs);

--- a/dom/media/gtest/TestGMPCrossOrigin.cpp
+++ b/dom/media/gtest/TestGMPCrossOrigin.cpp
@@ -19,20 +19,16 @@
 #include "nsISimpleEnumerator.h"
 #include "mozilla/Atomics.h"
 #include "nsNSSComponent.h"
 #include "mozilla/DebugOnly.h"
 #include "GMPDeviceBinding.h"
 #include "mozilla/dom/MediaKeyStatusMapBinding.h" // For MediaKeyStatus
 #include "mozilla/dom/MediaKeyMessageEventBinding.h" // For MediaKeyMessageType
 
-#if defined(XP_WIN)
-#include "mozilla/WindowsVersion.h"
-#endif
-
 using namespace std;
 
 using namespace mozilla;
 using namespace mozilla::gmp;
 
 struct GMPTestRunner
 {
   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(GMPTestRunner)
@@ -1530,21 +1526,16 @@ TEST(GeckoMediaPlugins, GMPStorageAsyncS
 
 TEST(GeckoMediaPlugins, GMPPluginVoucher) {
   RefPtr<GMPStorageTest> runner = new GMPStorageTest();
   runner->DoTest(&GMPStorageTest::TestPluginVoucher);
 }
 
 #if defined(XP_WIN)
 TEST(GeckoMediaPlugins, GMPOutputProtection) {
-  // Output Protection is not available pre-Vista.
-  if (!IsVistaOrLater()) {
-    return;
-  }
-
   RefPtr<GMPStorageTest> runner = new GMPStorageTest();
   runner->DoTest(&GMPStorageTest::TestOutputProtection);
 }
 #endif
 
 TEST(GeckoMediaPlugins, GMPStorageGetRecordNamesInMemoryStorage) {
   RefPtr<GMPStorageTest> runner = new GMPStorageTest();
   runner->DoTest(&GMPStorageTest::TestGetRecordNamesInMemoryStorage);