--- a/dom/media/eme/EMEUtils.cpp
+++ b/dom/media/eme/EMEUtils.cpp
@@ -143,9 +143,15 @@ KeySystemToGMPName(const nsAString& aKey
   }
   if (aKeySystem.EqualsLiteral("com.widevine.alpha")) {
     return NS_LITERAL_STRING("gmp-widevinecdm");
   }
   MOZ_ASSERT(false, "We should only call this for known GMPs");
   return EmptyString();
 }
 
+bool
+IsClearkeyKeySystem(const nsAString& aKeySystem)
+{
+  return aKeySystem.EqualsLiteral("org.w3.clearkey");
+}
+
 } // namespace mozilla

--- a/dom/media/eme/EMEUtils.h
+++ b/dom/media/eme/EMEUtils.h
@@ -97,11 +97,14 @@ struct ArrayData {
 //
 // Only call this on a properly initialized ArrayBufferViewOrArrayBuffer.
 ArrayData
 GetArrayBufferViewOrArrayBufferData(const dom::ArrayBufferViewOrArrayBuffer& aBufferOrView);
 
 nsString
 KeySystemToGMPName(const nsAString& aKeySystem);
 
+bool
+IsClearkeyKeySystem(const nsAString& aKeySystem);
+
 } // namespace mozilla
 
 #endif // EME_LOG_H_

--- a/dom/media/eme/MediaKeySystemAccess.cpp
+++ b/dom/media/eme/MediaKeySystemAccess.cpp
@@ -263,29 +263,25 @@ EnsureMinCDMVersion(mozIGeckoMediaPlugin
 
 /* static */
 MediaKeySystemStatus
 MediaKeySystemAccess::GetKeySystemStatus(const nsAString& aKeySystem,
                                          int32_t aMinCdmVersion,
                                          nsACString& aOutMessage,
                                          nsACString& aOutCdmVersion)
 {
-  MOZ_ASSERT(MediaPrefs::EMEEnabled());
+  MOZ_ASSERT(MediaPrefs::EMEEnabled() || IsClearkeyKeySystem(aKeySystem));
   nsCOMPtr<mozIGeckoMediaPluginService> mps =
     do_GetService("@mozilla.org/gecko-media-plugin-service;1");
   if (NS_WARN_IF(!mps)) {
     aOutMessage = NS_LITERAL_CSTRING("Failed to get GMP service");
     return MediaKeySystemStatus::Error;
   }
 
   if (aKeySystem.EqualsLiteral("org.w3.clearkey")) {
-    if (!Preferences::GetBool("media.eme.clearkey.enabled", true)) {
-      aOutMessage = NS_LITERAL_CSTRING("ClearKey was disabled");
-      return MediaKeySystemStatus::Cdm_disabled;
-    }
     return EnsureMinCDMVersion(mps, aKeySystem, aMinCdmVersion, aOutMessage, aOutCdmVersion);
   }
 
   if (Preferences::GetBool("media.gmp-eme-adobe.visible", false)) {
     if (aKeySystem.EqualsLiteral("com.adobe.primetime")) {
       if (!Preferences::GetBool("media.gmp-eme-adobe.enabled", false)) {
         aOutMessage = NS_LITERAL_CSTRING("Adobe EME disabled");
         return MediaKeySystemStatus::Cdm_disabled;

--- a/dom/media/eme/MediaKeySystemAccessManager.cpp
+++ b/dom/media/eme/MediaKeySystemAccessManager.cpp
@@ -107,18 +107,20 @@ MediaKeySystemAccessManager::Request(Det
     aPromise->MaybeReject(NS_ERROR_DOM_NOT_SUPPORTED_ERR,
                           NS_LITERAL_CSTRING("Key system string is invalid,"
                                              " or key system is unsupported"));
     diagnostics.StoreMediaKeySystemAccess(mWindow->GetExtantDoc(),
                                           aKeySystem, false, __func__);
     return;
   }
 
-  if (!MediaPrefs::EMEEnabled()) {
+  if (!MediaPrefs::EMEEnabled() && !IsClearkeyKeySystem(aKeySystem)) {
     // EME disabled by user, send notification to chrome so UI can inform user.
+    // Clearkey is allowed even when EME is disabled because we want the pref
+    // "media.eme.enabled" only taking effect on proprietary DRMs.
     MediaKeySystemAccess::NotifyObservers(mWindow,
                                           aKeySystem,
                                           MediaKeySystemStatus::Api_disabled);
     aPromise->MaybeReject(NS_ERROR_DOM_NOT_SUPPORTED_ERR,
                           NS_LITERAL_CSTRING("EME has been preffed off"));
     diagnostics.StoreMediaKeySystemAccess(mWindow->GetExtantDoc(),
                                           aKeySystem, false, __func__);
     return;

--- a/dom/media/test/test_eme_request_notifications.html
+++ b/dom/media/test/test_eme_request_notifications.html
@@ -57,46 +57,39 @@ function Test(test) {
       );
     });
   });
 }
 
 var tests = [
   {
     keySystem: CLEARKEY_KEYSYSTEM,
-    shouldPass: false,
-    expectedStatus: 'api-disabled',
-    prefs: [["media.eme.enabled", false], ["media.eme.clearkey.enabled", true]]
+    shouldPass: true,
+    expectedStatus: 'cdm-created',
+    prefs: [["media.eme.enabled", false]]
   },
   {
-    keySystem: CLEARKEY_KEYSYSTEM,
-    shouldPass: false,
-    expectedStatus: 'cdm-disabled',
-    prefs: [["media.eme.enabled", true], ["media.eme.clearkey.enabled", false]]
-  },
-  {
-    keySystem: CLEARKEY_KEYSYSTEM + '.10000' , // A stupendously high min CDM version, presumably not installed.
+    keySystem: CLEARKEY_KEYSYSTEM + '.10000', // A stupendously high min CDM version, presumably not installed.
     shouldPass: false,
     expectedStatus: 'cdm-insufficient-version',
-    prefs: [["media.eme.enabled", true], ["media.eme.clearkey.enabled", true]]
+    prefs: [["media.eme.enabled", true]]
   },
   {
     keySystem: CLEARKEY_KEYSYSTEM,
     shouldPass: true,
     expectedStatus: 'cdm-created',
-    prefs: [["media.eme.enabled", true], ["media.eme.clearkey.enabled", true]]
+    prefs: [["media.eme.enabled", true]]
   },
 ];
 
 SetupEMEPref(function() {
   tests.reduce(function(p,c,i,array) {
     return p.then(function() { return Test(c); });
   }, Promise.resolve()).then(SimpleTest.finish);
 });
 
 
 SimpleTest.waitForExplicitFinish();
 
 </script>
 </pre>
 </body>
 </html>
-

--- a/toolkit/mozapps/extensions/internal/GMPProvider.jsm
+++ b/toolkit/mozapps/extensions/internal/GMPProvider.jsm
@@ -596,30 +596,27 @@ var GMPProvider = {
           if (e.name != 'NS_ERROR_NOT_AVAILABLE')
             throw e;
           this._log.warn("startup - adding gmp directory failed with " +
                          e.name + " - sandboxing not available?", e);
         }
       }
     }
 
-    var emeEnabled = Preferences.get(GMPPrefs.KEY_EME_ENABLED, false);
-    if (emeEnabled) {
-      try {
-        let greDir = Services.dirsvc.get(NS_GRE_DIR,
-                                         Ci.nsILocalFile);
-        let clearkeyPath = OS.Path.join(greDir.path,
-                                        CLEARKEY_PLUGIN_ID,
-                                        CLEARKEY_VERSION);
-        this._log.info("startup - adding clearkey CDM directory " +
-                       clearkeyPath);
-        gmpService.addPluginDirectory(clearkeyPath);
-      } catch (e) {
-        this._log.warn("startup - adding clearkey CDM failed", e);
-      }
+    try {
+      let greDir = Services.dirsvc.get(NS_GRE_DIR,
+                                       Ci.nsILocalFile);
+      let clearkeyPath = OS.Path.join(greDir.path,
+                                      CLEARKEY_PLUGIN_ID,
+                                      CLEARKEY_VERSION);
+      this._log.info("startup - adding clearkey CDM directory " +
+                     clearkeyPath);
+      gmpService.addPluginDirectory(clearkeyPath);
+    } catch (e) {
+      this._log.warn("startup - adding clearkey CDM failed", e);
     }
   },
 
   shutdown: function() {
     this._log.trace("shutdown");
     Preferences.ignore(GMPPrefs.KEY_LOG_BASE, configureLogging);
 
     let shutdownTask = Task.spawn(function*() {