--- a/startupcache/StartupCache.cpp
+++ b/startupcache/StartupCache.cpp
@@ -14,17 +14,16 @@
 #include "nsClassHashtable.h"
 #include "nsComponentManagerUtils.h"
 #include "nsDirectoryServiceUtils.h"
 #include "nsIClassInfo.h"
 #include "nsIFile.h"
 #include "nsIObserver.h"
 #include "nsIObserverService.h"
 #include "nsIOutputStream.h"
-#include "nsIStartupCache.h"
 #include "nsIStorageStream.h"
 #include "nsIStreamBufferAccess.h"
 #include "nsIStringStream.h"
 #include "nsISupports.h"
 #include "nsITimer.h"
 #include "nsIZipWriter.h"
 #include "nsIZipReader.h"
 #include "nsWeakReference.h"
@@ -691,83 +690,10 @@ StartupCacheDebugOutputStream::GetBuffer
 
 void
 StartupCacheDebugOutputStream::PutBuffer(char* aBuffer, uint32_t aLength)
 {
   mBinaryStream->PutBuffer(aBuffer, aLength);
 }
 #endif //DEBUG
 
-StartupCacheWrapper* StartupCacheWrapper::gStartupCacheWrapper = nullptr;
-
-NS_IMPL_ISUPPORTS(StartupCacheWrapper, nsIStartupCache)
-
-StartupCacheWrapper::~StartupCacheWrapper()
-{
-  MOZ_ASSERT(gStartupCacheWrapper == this);
-  gStartupCacheWrapper = nullptr;
-}
-
-already_AddRefed<StartupCacheWrapper> StartupCacheWrapper::GetSingleton()
-{
-  if (!gStartupCacheWrapper)
-    gStartupCacheWrapper = new StartupCacheWrapper();
-
-  return do_AddRef(gStartupCacheWrapper);
-}
-
-nsresult
-StartupCacheWrapper::GetBuffer(const char* id, char** outbuf, uint32_t* length)
-{
-  StartupCache* sc = StartupCache::GetSingleton();
-  if (!sc) {
-    return NS_ERROR_NOT_INITIALIZED;
-  }
-  UniquePtr<char[]> buf;
-  nsresult rv = sc->GetBuffer(id, &buf, length);
-  *outbuf = buf.release();
-  return rv;
-}
-
-nsresult
-StartupCacheWrapper::PutBuffer(const char* id, const char* inbuf, uint32_t length)
-{
-  StartupCache* sc = StartupCache::GetSingleton();
-  if (!sc) {
-    return NS_ERROR_NOT_INITIALIZED;
-  }
-  return sc->PutBuffer(id, inbuf, length);
-}
-
-nsresult
-StartupCacheWrapper::InvalidateCache()
-{
-  StartupCache* sc = StartupCache::GetSingleton();
-  if (!sc) {
-    return NS_ERROR_NOT_INITIALIZED;
-  }
-  sc->InvalidateCache();
-  return NS_OK;
-}
-
-nsresult
-StartupCacheWrapper::GetDebugObjectOutputStream(nsIObjectOutputStream* stream,
-                                                nsIObjectOutputStream** outStream)
-{
-  StartupCache* sc = StartupCache::GetSingleton();
-  if (!sc) {
-    return NS_ERROR_NOT_INITIALIZED;
-  }
-  return sc->GetDebugObjectOutputStream(stream, outStream);
-}
-
-nsresult
-StartupCacheWrapper::GetObserver(nsIObserver** obv) {
-  StartupCache* sc = StartupCache::GetSingleton();
-  if (!sc) {
-    return NS_ERROR_NOT_INITIALIZED;
-  }
-  NS_ADDREF(*obv = sc->mListener);
-  return NS_OK;
-}
-
 } // namespace scache
 } // namespace mozilla

--- a/startupcache/StartupCache.h
+++ b/startupcache/StartupCache.h
@@ -5,26 +5,25 @@
 
 #ifndef StartupCache_h_
 #define StartupCache_h_
 
 #include "nsClassHashtable.h"
 #include "nsComponentManagerUtils.h"
 #include "nsTArray.h"
 #include "nsZipArchive.h"
-#include "nsIStartupCache.h"
 #include "nsITimer.h"
 #include "nsIMemoryReporter.h"
 #include "nsIObserverService.h"
 #include "nsIObserver.h"
+#include "nsIObjectOutputStream.h"
 #include "nsIOutputStream.h"
 #include "nsIFile.h"
 #include "mozilla/Attributes.h"
 #include "mozilla/MemoryReporting.h"
-#include "mozilla/StaticPtr.h"
 #include "mozilla/UniquePtr.h"
 
 /**
  * The StartupCache is a persistent cache of simple key-value pairs,
  * where the keys are null-terminated c-strings and the values are
  * arbitrary data, passed as a (char*, size) tuple.
  *
  * Clients should use the GetSingleton() static method to access the cache. It
@@ -99,17 +98,16 @@ class StartupCacheListener final : publi
   NS_DECL_THREADSAFE_ISUPPORTS
   NS_DECL_NSIOBSERVER
 };
 
 class StartupCache : public nsIMemoryReporter
 {
 
 friend class StartupCacheListener;
-friend class StartupCacheWrapper;
 
 public:
   NS_DECL_THREADSAFE_ISUPPORTS
   NS_DECL_NSIMEMORYREPORTER
 
   // StartupCache methods. See above comments for a more detailed description.
 
   // Returns a buffer that was previously stored, caller takes ownership.
@@ -195,30 +193,12 @@ class StartupCacheDebugOutputStream fina
 
   bool CheckReferences(nsISupports* aObject);
 
   nsCOMPtr<nsIObjectOutputStream> mBinaryStream;
   nsTHashtable<nsISupportsHashKey> *mObjectMap;
 };
 #endif // DEBUG
 
-// XPCOM wrapper interface provided for tests only.
-#define NS_STARTUPCACHE_CID \
-      {0xae4505a9, 0x87ab, 0x477c, \
-      {0xb5, 0x77, 0xf9, 0x23, 0x57, 0xed, 0xa8, 0x84}}
-// contract id: "@mozilla.org/startupcache/cache;1"
-
-class StartupCacheWrapper final
-  : public nsIStartupCache
-{
-  ~StartupCacheWrapper();
-
-  NS_DECL_THREADSAFE_ISUPPORTS
-  NS_DECL_NSISTARTUPCACHE
-
-  static already_AddRefed<StartupCacheWrapper> GetSingleton();
-  static StartupCacheWrapper *gStartupCacheWrapper;
-};
-
 } // namespace scache
 } // namespace mozilla
 
 #endif //StartupCache_h_

deleted file mode 100644
--- a/startupcache/StartupCacheModule.cpp
+++ /dev/null
@@ -1,45 +0,0 @@
-/* -*-  Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2; -*- */
-/* 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 <string.h>
-
-#include "nscore.h"
-
-#include "nsID.h"
-#include "nsIComponentManager.h"
-#include "nsIServiceManager.h"
-#include "nsCOMPtr.h"
-#include "nsIModule.h"
-#include "mozilla/ModuleUtils.h"
-#include "mozilla/scache/StartupCache.h"
-
-using namespace mozilla::scache;
-
-// XXX Need help with guard for ENABLE_TEST
-NS_GENERIC_FACTORY_SINGLETON_CONSTRUCTOR(StartupCacheWrapper,
-                                         StartupCacheWrapper::GetSingleton)
-NS_DEFINE_NAMED_CID(NS_STARTUPCACHE_CID);
-
-static const mozilla::Module::CIDEntry kStartupCacheCIDs[] = {
-    { &kNS_STARTUPCACHE_CID, false, nullptr, StartupCacheWrapperConstructor },
-    { nullptr }
-};
-
-static const mozilla::Module::ContractIDEntry kStartupCacheContracts[] = {
-    { "@mozilla.org/startupcache/cache;1", &kNS_STARTUPCACHE_CID },
-    { nullptr }
-};
-
-static const mozilla::Module kStartupCacheModule = {
-    mozilla::Module::kVersion,
-    kStartupCacheCIDs,
-    kStartupCacheContracts,
-    nullptr,
-    nullptr,
-    nullptr,
-    nullptr
-};
-
-NSMODULE_DEFN(StartupCacheModule) = &kStartupCacheModule;

--- a/startupcache/StartupCacheUtils.h
+++ b/startupcache/StartupCacheUtils.h
@@ -28,17 +28,17 @@ NewObjectInputStreamFromBuffer(UniquePtr
 // instead of references).
 nsresult
 NewObjectOutputWrappedStorageStream(nsIObjectOutputStream **wrapperStream,
                                     nsIStorageStream** stream,
                                     bool wantDebugStream);
 
 // Creates a buffer for storing the stream into the cache. The buffer is
 // allocated with 'new []'.  After calling this function, the caller would
-// typically call nsIStartupCache::PutBuffer with the returned buffer.
+// typically call StartupCache::PutBuffer with the returned buffer.
 nsresult
 NewBufferFromStorageStream(nsIStorageStream *storageStream,
                            UniquePtr<char[]>* buffer, uint32_t* len);
 
 nsresult
 ResolveURI(nsIURI *in, nsIURI **out);
 
 nsresult

--- a/startupcache/moz.build
+++ b/startupcache/moz.build
@@ -4,26 +4,19 @@
 # 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/.
 
 with Files("**"):
     BUG_COMPONENT = ("Core", "XPCOM")
 
 TEST_DIRS += ['test']
 
-XPIDL_SOURCES += [
-    'nsIStartupCache.idl',
-]
-
-XPIDL_MODULE = 'startupcache'
-
 EXPORTS.mozilla.scache += [
     'StartupCache.h',
     'StartupCacheUtils.h',
 ]
 
 UNIFIED_SOURCES += [
     'StartupCache.cpp',
-    'StartupCacheModule.cpp',
     'StartupCacheUtils.cpp',
 ]
 
 FINAL_LIBRARY = 'xul'

deleted file mode 100644
--- a/startupcache/nsIStartupCache.idl
+++ /dev/null
@@ -1,53 +0,0 @@
-/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
- *
- * 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 "nsIInputStream.idl"
-#include "nsISupports.idl"
-#include "nsIObserver.idl"
-#include "nsIObjectOutputStream.idl"
-
-%{C++
-#include "mozilla/UniquePtr.h"
-%}
-
-[uuid(25957820-90a1-428c-8739-b0845d3cc534)]
-interface nsIStartupCache : nsISupports
-{
-
-  /** This interface is provided for testing purposes only, basically
-   *  just to solve link vagaries. See docs in StartupCache.h
-   *  GetBuffer, PutBuffer, and InvalidateCache act as described 
-   *  in that file. */
-
-  uint32_t getBuffer(in string aID, out charPtr aBuffer);
-%{C++
-  /* A more convenient interface for using from C++.  */
-  nsresult GetBuffer(const char* id, mozilla::UniquePtr<char[]>* outbuf, uint32_t* length)
-  {
-    char* buf;
-    nsresult rv = GetBuffer(id, &buf, length);
-    NS_ENSURE_SUCCESS(rv, rv);
-    outbuf->reset(buf);
-    return rv;
-  }
-%}
-
-  void putBuffer(in string aID, in string aBuffer, 
-                            in uint32_t aLength);
- 
-  void invalidateCache();
-  
-
-  /** In debug builds, wraps this object output stream with a stream that will 
-   *  detect and prevent the write of a multiply-referenced non-singleton object 
-   *  during serialization. In non-debug, returns an add-ref'd pointer to
-   *  original stream, unwrapped. */
-  nsIObjectOutputStream getDebugObjectOutputStream(in nsIObjectOutputStream aStream);
-
-  /* Allows clients to simulate the behavior of ObserverService. */
-  readonly attribute nsIObserver observer;
-};
-