--- a/dom/base/Navigator.cpp
+++ b/dom/base/Navigator.cpp
@@ -1899,114 +1899,25 @@ Navigator::GetUserAgent(nsPIDOMWindowInn
       return rv;
     }
     CopyASCIItoUTF16(userAgent, aUserAgent);
   }
   return NS_OK;
 }
 
 static nsCString
-ToCString(const nsString& aString)
-{
-  nsCString str("'");
-  str.Append(NS_ConvertUTF16toUTF8(aString));
-  str.AppendLiteral("'");
-  return str;
-}
-
-static nsCString
-ToCString(const MediaKeysRequirement aValue)
-{
-  nsCString str("'");
-  str.Append(nsDependentCString(MediaKeysRequirementValues::strings[static_cast<uint32_t>(aValue)].value));
-  str.AppendLiteral("'");
-  return str;
-}
-
-static nsCString
-ToCString(const MediaKeySystemMediaCapability& aValue)
-{
-  nsCString str;
-  str.AppendLiteral("{contentType=");
-  str.Append(ToCString(aValue.mContentType));
-  str.AppendLiteral(", robustness=");
-  str.Append(ToCString(aValue.mRobustness));
-  str.AppendLiteral("}");
-  return str;
-}
-
-template<class Type>
-static nsCString
-ToCString(const Sequence<Type>& aSequence)
-{
-  nsCString str;
-  str.AppendLiteral("[");
-  for (size_t i = 0; i < aSequence.Length(); i++) {
-    if (i != 0) {
-      str.AppendLiteral(",");
-    }
-    str.Append(ToCString(aSequence[i]));
-  }
-  str.AppendLiteral("]");
-  return str;
-}
-
-template<class Type>
-static nsCString
-ToCString(const Optional<Sequence<Type>>& aOptional)
-{
-  nsCString str;
-  if (aOptional.WasPassed()) {
-    str.Append(ToCString(aOptional.Value()));
-  } else {
-    str.AppendLiteral("[]");
-  }
-  return str;
-}
-
-static nsCString
-ToCString(const MediaKeySystemConfiguration& aConfig)
-{
-  nsCString str;
-  str.AppendLiteral("{label=");
-  str.Append(ToCString(aConfig.mLabel));
-
-  str.AppendLiteral(", initDataTypes=");
-  str.Append(ToCString(aConfig.mInitDataTypes));
-
-  str.AppendLiteral(", audioCapabilities=");
-  str.Append(ToCString(aConfig.mAudioCapabilities));
-
-  str.AppendLiteral(", videoCapabilities=");
-  str.Append(ToCString(aConfig.mVideoCapabilities));
-
-  str.AppendLiteral(", distinctiveIdentifier=");
-  str.Append(ToCString(aConfig.mDistinctiveIdentifier));
-
-  str.AppendLiteral(", persistentState=");
-  str.Append(ToCString(aConfig.mPersistentState));
-
-  str.AppendLiteral(", sessionTypes=");
-  str.Append(ToCString(aConfig.mSessionTypes));
-
-  str.AppendLiteral("}");
-
-  return str;
-}
-
-static nsCString
 RequestKeySystemAccessLogString(
   const nsAString& aKeySystem,
   const Sequence<MediaKeySystemConfiguration>& aConfigs,
   bool aIsSecureContext)
 {
   nsCString str;
   str.AppendPrintf("Navigator::RequestMediaKeySystemAccess(keySystem='%s' options=",
                    NS_ConvertUTF16toUTF8(aKeySystem).get());
-  str.Append(ToCString(aConfigs));
+  str.Append(MediaKeySystemAccess::ToCString(aConfigs));
   str.AppendLiteral(") secureContext=");
   str.AppendInt(aIsSecureContext);
   return str;
 }
 
 already_AddRefed<Promise>
 Navigator::RequestMediaKeySystemAccess(const nsAString& aKeySystem,
                                        const Sequence<MediaKeySystemConfiguration>& aConfigs,

--- a/dom/media/eme/MediaKeySystemAccess.cpp
+++ b/dom/media/eme/MediaKeySystemAccess.cpp
@@ -1091,10 +1091,108 @@ MediaKeySystemAccess::NotifyObservers(ns
   data.ToJSON(json);
   EME_LOG("MediaKeySystemAccess::NotifyObservers() %s", NS_ConvertUTF16toUTF8(json).get());
   nsCOMPtr<nsIObserverService> obs = services::GetObserverService();
   if (obs) {
     obs->NotifyObservers(aWindow, "mediakeys-request", json.get());
   }
 }
 
+static nsCString
+ToCString(const nsString& aString)
+{
+  nsCString str("'");
+  str.Append(NS_ConvertUTF16toUTF8(aString));
+  str.AppendLiteral("'");
+  return str;
+}
+
+static nsCString
+ToCString(const MediaKeysRequirement aValue)
+{
+  nsCString str("'");
+  str.Append(nsDependentCString(
+    MediaKeysRequirementValues::strings[static_cast<uint32_t>(aValue)].value));
+  str.AppendLiteral("'");
+  return str;
+}
+
+static nsCString
+ToCString(const MediaKeySystemMediaCapability& aValue)
+{
+  nsCString str;
+  str.AppendLiteral("{contentType=");
+  str.Append(ToCString(aValue.mContentType));
+  str.AppendLiteral(", robustness=");
+  str.Append(ToCString(aValue.mRobustness));
+  str.AppendLiteral("}");
+  return str;
+}
+
+template<class Type>
+static nsCString
+ToCString(const Sequence<Type>& aSequence)
+{
+  nsCString str;
+  str.AppendLiteral("[");
+  for (size_t i = 0; i < aSequence.Length(); i++) {
+    if (i != 0) {
+      str.AppendLiteral(",");
+    }
+    str.Append(ToCString(aSequence[i]));
+  }
+  str.AppendLiteral("]");
+  return str;
+}
+
+template<class Type>
+static nsCString
+ToCString(const Optional<Sequence<Type>>& aOptional)
+{
+  nsCString str;
+  if (aOptional.WasPassed()) {
+    str.Append(ToCString(aOptional.Value()));
+  } else {
+    str.AppendLiteral("[]");
+  }
+  return str;
+}
+
+static nsCString
+ToCString(const MediaKeySystemConfiguration& aConfig)
+{
+  nsCString str;
+  str.AppendLiteral("{label=");
+  str.Append(ToCString(aConfig.mLabel));
+
+  str.AppendLiteral(", initDataTypes=");
+  str.Append(ToCString(aConfig.mInitDataTypes));
+
+  str.AppendLiteral(", audioCapabilities=");
+  str.Append(ToCString(aConfig.mAudioCapabilities));
+
+  str.AppendLiteral(", videoCapabilities=");
+  str.Append(ToCString(aConfig.mVideoCapabilities));
+
+  str.AppendLiteral(", distinctiveIdentifier=");
+  str.Append(ToCString(aConfig.mDistinctiveIdentifier));
+
+  str.AppendLiteral(", persistentState=");
+  str.Append(ToCString(aConfig.mPersistentState));
+
+  str.AppendLiteral(", sessionTypes=");
+  str.Append(ToCString(aConfig.mSessionTypes));
+
+  str.AppendLiteral("}");
+
+  return str;
+}
+
+/* static */
+nsCString
+MediaKeySystemAccess::ToCString(
+  const Sequence<MediaKeySystemConfiguration>& aConfig)
+{
+  return mozilla::dom::ToCString(aConfig);
+}
+
 } // namespace dom
 } // namespace mozilla

--- a/dom/media/eme/MediaKeySystemAccess.h
+++ b/dom/media/eme/MediaKeySystemAccess.h
@@ -66,16 +66,19 @@ public:
     const Sequence<MediaKeySystemConfiguration>& aConfigs,
     MediaKeySystemConfiguration& aOutConfig,
     DecoderDoctorDiagnostics* aDiagnostics,
     bool aIsPrivateBrowsing);
 
   static bool KeySystemSupportsInitDataType(const nsAString& aKeySystem,
                                             const nsAString& aInitDataType);
 
+  static nsCString ToCString(
+    const Sequence<MediaKeySystemConfiguration>& aConfig);
+
 private:
   nsCOMPtr<nsPIDOMWindowInner> mParent;
   const nsString mKeySystem;
   const MediaKeySystemConfiguration mConfig;
 };
 
 } // namespace dom
 } // namespace mozilla