--- a/dom/media/AbstractMediaDecoder.h
+++ b/dom/media/AbstractMediaDecoder.h
@@ -12,31 +12,30 @@
 
 #include "FrameStatistics.h"
 #include "MediaEventSource.h"
 #include "MediaInfo.h"
 #include "nsISupports.h"
 #include "nsDataHashtable.h"
 #include "nsThreadUtils.h"
 
-class GMPCrashHelper;
-
 namespace mozilla
 {
 
 namespace layers
 {
   class ImageContainer;
   class KnowsCompositor;
 } // namespace layers
 class MediaResource;
 class ReentrantMonitor;
 class VideoFrameContainer;
 class MediaDecoderOwner;
 class CDMProxy;
+class GMPCrashHelper;
 
 typedef nsDataHashtable<nsCStringHashKey, nsCString> MetadataTags;
 
 static inline bool IsCurrentThread(nsIThread* aThread) {
   return NS_GetCurrentThread() == aThread;
 }
 
 /**

--- a/dom/media/MediaDecoder.cpp
+++ b/dom/media/MediaDecoder.cpp
@@ -26,17 +26,17 @@
 #include "mozilla/dom/AudioTrack.h"
 #include "mozilla/dom/AudioTrackList.h"
 #include "mozilla/dom/HTMLMediaElement.h"
 #include "mozilla/dom/Promise.h"
 #include "mozilla/dom/VideoTrack.h"
 #include "mozilla/dom/VideoTrackList.h"
 #include "nsPrintfCString.h"
 #include "mozilla/Telemetry.h"
-#include "GMPService.h"
+#include "GMPCrashHelper.h"
 #include "Layers.h"
 #include "mozilla/layers/ShadowLayers.h"
 
 #ifdef MOZ_ANDROID_OMX
 #include "AndroidBridge.h"
 #endif
 
 using namespace mozilla::dom;

--- a/dom/media/eme/MediaKeys.cpp
+++ b/dom/media/eme/MediaKeys.cpp
@@ -1,16 +1,16 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
 /* 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 "mozilla/dom/MediaKeys.h"
-#include "GMPService.h"
+#include "GMPCrashHelper.h"
 #include "mozilla/dom/HTMLMediaElement.h"
 #include "mozilla/dom/MediaKeysBinding.h"
 #include "mozilla/dom/MediaKeyMessageEvent.h"
 #include "mozilla/dom/MediaKeyError.h"
 #include "mozilla/dom/MediaKeySession.h"
 #include "mozilla/dom/DOMException.h"
 #include "mozilla/dom/UnionTypes.h"
 #include "mozilla/Telemetry.h"

new file mode 100644
--- /dev/null
+++ b/dom/media/gmp/GMPCrashHelper.cpp
@@ -0,0 +1,26 @@
+/* -*- 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 "GMPCrashHelper.h"
+#include "runnable_utils.h"
+#include "nsThreadUtils.h"
+
+namespace mozilla {
+
+NS_IMPL_ADDREF(GMPCrashHelper)
+NS_IMPL_RELEASE_WITH_DESTROY(GMPCrashHelper, Destroy())
+
+void
+GMPCrashHelper::Destroy()
+{
+  if (NS_IsMainThread()) {
+    delete this;
+  } else {
+    // Don't addref, as then we'd end up releasing after the detele runs!
+    NS_DispatchToMainThread(mozilla::NewNonOwningRunnableMethod(this, &GMPCrashHelper::Destroy));
+  }
+}
+
+} // namespace mozilla

new file mode 100644
--- /dev/null
+++ b/dom/media/gmp/GMPCrashHelper.h
@@ -0,0 +1,41 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* 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/. */
+
+#if !defined(GMPCrashHelper_h_)
+#define GMPCrashHelper_h_
+
+#include "nsPIDOMWindow.h"
+#include "nsISupportsImpl.h"
+
+namespace mozilla {
+
+// For every GMP actor requested, the caller can specify a crash helper,
+// which is an object which supplies the nsPIDOMWindowInner to which we'll
+// dispatch the PluginCrashed event if the GMP crashes.
+// GMPCrashHelper has threadsafe refcounting. Its release method ensures
+// that instances are destroyed on the main thread.
+class GMPCrashHelper
+{
+public:
+  NS_METHOD_(MozExternalRefCountType) AddRef(void);
+  NS_METHOD_(MozExternalRefCountType) Release(void);
+
+  // Called on the main thread.
+  virtual already_AddRefed<nsPIDOMWindowInner> GetPluginCrashedEventTarget() = 0;
+
+protected:
+  virtual ~GMPCrashHelper()
+  {
+    MOZ_ASSERT(NS_IsMainThread());
+  }
+  void Destroy();
+  mozilla::ThreadSafeAutoRefCnt mRefCnt;
+  NS_DECL_OWNINGTHREAD
+};
+
+} // namespace mozilla
+
+#endif // GMPCrashHelper_h_

--- a/dom/media/gmp/GMPCrashHelperHolder.h
+++ b/dom/media/gmp/GMPCrashHelperHolder.h
@@ -6,19 +6,19 @@
 #ifndef GMPCrashHelperHolder_h_
 #define GMPCrashHelperHolder_h_
 
 #include "GMPService.h"
 #include "mozilla/RefPtr.h"
 #include "nsPIDOMWindow.h"
 #include "mozilla/ipc/ProtocolUtils.h"
 
-class GMPCrashHelper;
+namespace mozilla {
 
-namespace mozilla {
+class GMPCrashHelper;
 
 // Disconnecting the GMPCrashHelpers at the right time is hard. We need to
 // ensure that in the crashing case that we stay connected until the
 // "gmp-plugin-crashed" message is processed in the content process.
 //
 // We have two channels connecting to the GMP; PGMP which connects from
 // chrome to GMP process, and PGMPContent, which bridges between the content
 // and GMP process. If the GMP crashes both PGMP and PGMPContent receive

--- a/dom/media/gmp/GMPService.cpp
+++ b/dom/media/gmp/GMPService.cpp
@@ -30,16 +30,17 @@
 #endif
 #include "nsAppDirectoryServiceDefs.h"
 #include "nsDirectoryServiceUtils.h"
 #include "nsDirectoryServiceDefs.h"
 #include "nsHashKeys.h"
 #include "nsIFile.h"
 #include "nsISimpleEnumerator.h"
 #include "nsThreadUtils.h"
+#include "GMPCrashHelper.h"
 
 #include "mozilla/dom/PluginCrashedEvent.h"
 #include "mozilla/EventDispatcher.h"
 #include "mozilla/Attributes.h"
 
 namespace mozilla {
 
 #ifdef LOG
@@ -547,22 +548,8 @@ void GeckoMediaPluginService::Disconnect
     if (helpers->IsEmpty()) {
       iter.Remove();
     }
   }
 }
 
 } // namespace gmp
 } // namespace mozilla
-
-NS_IMPL_ADDREF(GMPCrashHelper)
-NS_IMPL_RELEASE_WITH_DESTROY(GMPCrashHelper, Destroy())
-
-void
-GMPCrashHelper::Destroy()
-{
-  if (NS_IsMainThread()) {
-    delete this;
-  } else {
-    // Don't addref, as then we'd end up releasing after the detele runs!
-    NS_DispatchToMainThread(mozilla::NewNonOwningRunnableMethod(this, &GMPCrashHelper::Destroy));
-  }
-}

--- a/dom/media/gmp/GMPService.h
+++ b/dom/media/gmp/GMPService.h
@@ -11,50 +11,27 @@
 #include "nsIObserver.h"
 #include "nsTArray.h"
 #include "mozilla/Attributes.h"
 #include "mozilla/Monitor.h"
 #include "nsString.h"
 #include "nsCOMPtr.h"
 #include "nsIThread.h"
 #include "nsThreadUtils.h"
-#include "nsPIDOMWindow.h"
 #include "nsIDocument.h"
 #include "nsIWeakReference.h"
 #include "mozilla/AbstractThread.h"
 #include "nsClassHashtable.h"
 #include "nsISupportsImpl.h"
 
 template <class> struct already_AddRefed;
 
-// For every GMP actor requested, the caller can specify a crash helper,
-// which is an object which supplies the nsPIDOMWindowInner to which we'll
-// dispatch the PluginCrashed event if the GMP crashes.
-// GMPCrashHelper has threadsafe refcounting. Its release method ensures
-// that instances are destroyed on the main thread.
-class GMPCrashHelper
-{
-public:
-  NS_METHOD_(MozExternalRefCountType) AddRef(void);
-  NS_METHOD_(MozExternalRefCountType) Release(void);
+namespace mozilla {
 
-  // Called on the main thread.
-  virtual already_AddRefed<nsPIDOMWindowInner> GetPluginCrashedEventTarget() = 0;
-
-protected:
-  virtual ~GMPCrashHelper()
-  {
-    MOZ_ASSERT(NS_IsMainThread());
-  }
-  void Destroy();
-  mozilla::ThreadSafeAutoRefCnt mRefCnt;
-  NS_DECL_OWNINGTHREAD
-};
-
-namespace mozilla {
+class GMPCrashHelper;
 
 extern LogModule* GetGMPLog();
 
 namespace gmp {
 
 class GetGMPContentParentCallback;
 
 class GeckoMediaPluginService : public mozIGeckoMediaPluginService

--- a/dom/media/gmp/moz.build
+++ b/dom/media/gmp/moz.build
@@ -35,16 +35,17 @@ EXPORTS += [
     'GMPAudioDecoderProxy.h',
     'GMPAudioHost.h',
     'GMPCallbackBase.h',
     'GMPCDMCallbackProxy.h',
     'GMPCDMProxy.h',
     'GMPChild.h',
     'GMPContentChild.h',
     'GMPContentParent.h',
+    'GMPCrashHelper.h',
     'GMPCrashHelperHolder.h',
     'GMPDecryptorChild.h',
     'GMPDecryptorParent.h',
     'GMPDecryptorProxy.h',
     'GMPEncryptedBufferDataImpl.h',
     'GMPLoader.h',
     'GMPMessageUtils.h',
     'GMPParent.h',
@@ -87,16 +88,17 @@ UNIFIED_SOURCES += [
     'GMPAudioDecoderChild.cpp',
     'GMPAudioDecoderParent.cpp',
     'GMPAudioHost.cpp',
     'GMPCDMCallbackProxy.cpp',
     'GMPCDMProxy.cpp',
     'GMPChild.cpp',
     'GMPContentChild.cpp',
     'GMPContentParent.cpp',
+    'GMPCrashHelper.cpp',
     'GMPDecryptorChild.cpp',
     'GMPDecryptorParent.cpp',
     'GMPDiskStorage.cpp',
     'GMPEncryptedBufferDataImpl.cpp',
     'GMPMemoryStorage.cpp',
     'GMPParent.cpp',
     'GMPPlatform.cpp',
     'GMPProcessChild.cpp',

--- a/dom/media/gmp/mozIGeckoMediaPluginService.idl
+++ b/dom/media/gmp/mozIGeckoMediaPluginService.idl
@@ -10,17 +10,20 @@
 #include "mozilla/UniquePtr.h"
 #include "nsTArray.h"
 #include "nsStringGlue.h"
 class GMPAudioDecoderProxy;
 class GMPDecryptorProxy;
 class GMPVideoDecoderProxy;
 class GMPVideoEncoderProxy;
 class GMPVideoHost;
+
+namespace mozilla {
 class GMPCrashHelper;
+}
 
 template<class T>
 class GMPGetterCallback
 {
 public:
   GMPGetterCallback() { MOZ_COUNT_CTOR(GMPGetterCallback<T>); }
   virtual ~GMPGetterCallback() { MOZ_COUNT_DTOR(GMPGetterCallback<T>); }
   virtual void Done(T*) = 0;
@@ -47,17 +50,17 @@ public:
 %}
 
 [ptr] native TagArray(nsTArray<nsCString>);
 native GetGMPDecryptorCallback(mozilla::UniquePtr<GetGMPDecryptorCallback>&&);
 native GetGMPAudioDecoderCallback(mozilla::UniquePtr<GetGMPAudioDecoderCallback>&&);
 native GetGMPVideoDecoderCallback(mozilla::UniquePtr<GetGMPVideoDecoderCallback>&&);
 native GetGMPVideoEncoderCallback(mozilla::UniquePtr<GetGMPVideoEncoderCallback>&&);
 native GetNodeIdCallback(mozilla::UniquePtr<GetNodeIdCallback>&&);
-native GMPCrashHelperPtr(GMPCrashHelper*);
+native GMPCrashHelperPtr(mozilla::GMPCrashHelper*);
 
 [scriptable, uuid(44d362ae-937a-4803-bee6-f2512a0149d1)]
 interface mozIGeckoMediaPluginService : nsISupports
 {
 
   /**
    * The GMP thread. Callable from any thread.
    */

--- a/dom/media/platforms/PlatformDecoderModule.h
+++ b/dom/media/platforms/PlatformDecoderModule.h
@@ -9,17 +9,17 @@
 
 #include "MediaDecoderReader.h"
 #include "MediaInfo.h"
 #include "mozilla/MozPromise.h"
 #include "mozilla/layers/LayersTypes.h"
 #include "mozilla/layers/KnowsCompositor.h"
 #include "nsTArray.h"
 #include "mozilla/RefPtr.h"
-#include "GMPService.h"
+#include "GMPCrashHelper.h"
 #include <queue>
 #include "MediaResult.h"
 
 namespace mozilla {
 class TrackInfo;
 class AudioInfo;
 class VideoInfo;
 class MediaRawData;

--- a/dom/media/webaudio/BufferDecoder.cpp
+++ b/dom/media/webaudio/BufferDecoder.cpp
@@ -3,17 +3,17 @@
 /* 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 "BufferDecoder.h"
 
 #include "nsISupports.h"
 #include "MediaResource.h"
-#include "GMPService.h"
+#include "GMPCrashHelper.h"
 
 namespace mozilla {
 
 NS_IMPL_ISUPPORTS0(BufferDecoder)
 
 BufferDecoder::BufferDecoder(MediaResource* aResource, GMPCrashHelper* aCrashHelper)
   : mResource(aResource)
   , mCrashHelper(aCrashHelper)

--- a/dom/media/webaudio/MediaBufferDecoder.cpp
+++ b/dom/media/webaudio/MediaBufferDecoder.cpp
@@ -20,17 +20,17 @@
 #include "nsIScriptObjectPrincipal.h"
 #include "nsIScriptError.h"
 #include "nsMimeTypes.h"
 #include "VideoUtils.h"
 #include "WebAudioUtils.h"
 #include "mozilla/dom/Promise.h"
 #include "mozilla/Telemetry.h"
 #include "nsPrintfCString.h"
-#include "GMPService.h"
+#include "GMPCrashHelper.h"
 
 namespace mozilla {
 
 extern LazyLogModule gMediaDecoderLog;
 
 NS_IMPL_CYCLE_COLLECTION_CLASS(WebAudioDecodeJob)
 
 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(WebAudioDecodeJob)