--- a/dom/gamepad/Gamepad.h
+++ b/dom/gamepad/Gamepad.h
@@ -28,24 +28,16 @@ const int kStandardGamepadAxes = 4;
 const int kButtonLeftTrigger = 6;
 const int kButtonRightTrigger = 7;
 
 const int kLeftStickXAxis = 0;
 const int kLeftStickYAxis = 1;
 const int kRightStickXAxis = 2;
 const int kRightStickYAxis = 3;
 
-// Standard channel is used for managing gamepads that
-// are from GamepadPlatformService. VR channel
-// is for gamepads that are from VRManagerChild.
-enum class GamepadServiceType : uint16_t {
-  Standard,
-  VR,
-  NumGamepadServiceType
-};
 
 class Gamepad final : public nsISupports,
                       public nsWrapperCache
 {
 public:
   Gamepad(nsISupports* aParent,
           const nsAString& aID, uint32_t aIndex,
           GamepadMappingType aMapping,

--- a/dom/gamepad/GamepadManager.cpp
+++ b/dom/gamepad/GamepadManager.cpp
@@ -581,17 +581,18 @@ GamepadManager::SetWindowHasSeenGamepad(
 }
 
 void
 GamepadManager::Update(const GamepadChangeEvent& aEvent)
 {
   if (aEvent.type() == GamepadChangeEvent::TGamepadAdded) {
     const GamepadAdded& a = aEvent.get_GamepadAdded();
     AddGamepad(a.index(), a.id(),
-               a.mapping(), a.service_type(),
+               static_cast<GamepadMappingType>(a.mapping()),
+               a.service_type(),
                a.num_buttons(), a.num_axes());
     return;
   }
   if (aEvent.type() == GamepadChangeEvent::TGamepadRemoved) {
     const GamepadRemoved& a = aEvent.get_GamepadRemoved();
     RemoveGamepad(a.index(), a.service_type());
     return;
   }

--- a/dom/gamepad/GamepadManager.h
+++ b/dom/gamepad/GamepadManager.h
@@ -6,16 +6,17 @@
 
 #ifndef mozilla_dom_GamepadManager_h_
 #define mozilla_dom_GamepadManager_h_
 
 #include "nsIIPCBackgroundChildCreateCallback.h"
 #include "nsIObserver.h"
 // Needed for GamepadMappingType
 #include "mozilla/dom/GamepadBinding.h"
+#include "mozilla/dom/GamepadServiceType.h"
 
 class nsGlobalWindow;
 
 namespace mozilla {
 namespace gfx {
 class VRManagerChild;
 } // namespace gfx
 namespace dom {

--- a/dom/gamepad/GamepadPlatformService.cpp
+++ b/dom/gamepad/GamepadPlatformService.cpp
@@ -90,17 +90,17 @@ GamepadPlatformService::AddGamepad(const
 {
   // This method is called by monitor thread populated in
   // platform-dependent backends
   MOZ_ASSERT(XRE_IsParentProcess());
   MOZ_ASSERT(!NS_IsMainThread());
 
   uint32_t index = ++mGamepadIndex;
   GamepadAdded a(NS_ConvertUTF8toUTF16(nsDependentCString(aID)), index,
-                 aMapping, GamepadServiceType::Standard, aNumButtons, aNumAxes);
+                 static_cast<uint32_t>(aMapping), GamepadServiceType::Standard, aNumButtons, aNumAxes);
   NotifyGamepadChange<GamepadAdded>(a);
   return index;
 }
 
 void
 GamepadPlatformService::RemoveGamepad(uint32_t aIndex)
 {
   // This method is called by monitor thread populated in

--- a/dom/gamepad/GamepadServiceTest.cpp
+++ b/dom/gamepad/GamepadServiceTest.cpp
@@ -117,20 +117,18 @@ GamepadServiceTest::AddGamepad(const nsA
                                uint32_t aNumButtons,
                                uint32_t aNumAxes,
                                ErrorResult& aRv)
 {
   if (mShuttingDown) {
     return nullptr;
   }
 
-  // Because GamepadServiceTest::AddGamepad() is opened for Web API,
-  // we need to convert aMapping from uint32_t to GamepadMappingType here.
   GamepadAdded a(nsString(aID), 0,
-                 static_cast<GamepadMappingType>(aMapping),
+                 aMapping,
                  GamepadServiceType::Standard,
                  aNumButtons, aNumAxes);
   GamepadChangeEvent e(a);
   nsCOMPtr<nsIGlobalObject> go = do_QueryInterface(mWindow);
 
   RefPtr<Promise> p = Promise::Create(go, aRv);
   if (aRv.Failed()) {
     return nullptr;

--- a/dom/gamepad/ipc/GamepadEventTypes.ipdlh
+++ b/dom/gamepad/ipc/GamepadEventTypes.ipdlh
@@ -1,23 +1,25 @@
 /* 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/. */
 
-using mozilla::dom::GamepadMappingType from "mozilla/dom/GamepadMessageUtils.h";
 using mozilla::dom::GamepadServiceType from "mozilla/dom/GamepadMessageUtils.h";
 
 
 namespace mozilla {
 namespace dom {
 
 struct GamepadAdded {
   nsString id;
   uint32_t index;
-  GamepadMappingType mapping;
+  // Ideally, mapping should be a GamepadMappingType
+  // But, we have dependency problems in non MOZ_GAMEPAD
+  // platforms. Therefore, we make it as an uint32_t here.
+  uint32_t mapping;
   GamepadServiceType service_type;
   uint32_t num_buttons;
   uint32_t num_axes;
 };
 
 struct GamepadRemoved {
   uint32_t index;
   GamepadServiceType service_type;

--- a/dom/gamepad/ipc/GamepadMessageUtils.h
+++ b/dom/gamepad/ipc/GamepadMessageUtils.h
@@ -1,24 +1,18 @@
 
 #ifndef mozilla_dom_gamepad_GamepadMessageUtils_h
 #define mozilla_dom_gamepad_GamepadMessageUtils_h
 
 #include "ipc/IPCMessageUtils.h"
-#include "mozilla/dom/Gamepad.h"
+#include "mozilla/dom/GamepadServiceType.h"
 
 namespace IPC {
 
 template<>
-struct ParamTraits<mozilla::dom::GamepadMappingType> :
-  public ContiguousEnumSerializer<mozilla::dom::GamepadMappingType,
-                                  mozilla::dom::GamepadMappingType(mozilla::dom::GamepadMappingType::_empty),
-                                  mozilla::dom::GamepadMappingType(mozilla::dom::GamepadMappingType::EndGuard_)> {};
-
-template<>
 struct ParamTraits<mozilla::dom::GamepadServiceType> :
   public ContiguousEnumSerializer<mozilla::dom::GamepadServiceType,
                                   mozilla::dom::GamepadServiceType(0),
                                   mozilla::dom::GamepadServiceType(
                                   mozilla::dom::GamepadServiceType::NumGamepadServiceType)> {};
 } // namespace IPC
 
 #endif // mozilla_dom_gamepad_GamepadMessageUtils_h
\ No newline at end of file

new file mode 100644
--- /dev/null
+++ b/dom/gamepad/ipc/GamepadServiceType.h
@@ -0,0 +1,20 @@
+
+#ifndef mozilla_dom_GamepadServiceType_h_
+#define mozilla_dom_GamepadServiceType_h_
+
+namespace mozilla{
+namespace dom{
+
+// Standard channel is used for managing gamepads that
+// are from GamepadPlatformService. VR channel
+// is for gamepads that are from VRManagerChild.
+enum class GamepadServiceType : uint16_t {
+  Standard,
+  VR,
+  NumGamepadServiceType
+};
+
+}// namespace dom
+}// namespace mozilla
+
+#endif // mozilla_dom_GamepadServiceType_h_
\ No newline at end of file

--- a/dom/gamepad/ipc/GamepadTestChannelParent.cpp
+++ b/dom/gamepad/ipc/GamepadTestChannelParent.cpp
@@ -18,17 +18,17 @@ GamepadTestChannelParent::RecvGamepadTes
   RefPtr<GamepadPlatformService>  service =
     GamepadPlatformService::GetParentService();
   MOZ_ASSERT(service);
   if (aEvent.type() == GamepadChangeEvent::TGamepadAdded) {
     const GamepadAdded& a = aEvent.get_GamepadAdded();
     nsCString gamepadID;
     LossyCopyUTF16toASCII(a.id(), gamepadID);
     uint32_t index = service->AddGamepad(gamepadID.get(),
-                                         a.mapping(),
+                                         static_cast<GamepadMappingType>(a.mapping()),
                                          a.num_buttons(),
                                          a.num_axes());
     if (!mShuttingdown) {
       Unused << SendReplyGamepadIndex(aID, index);
     }
     return true;
   }
   if (aEvent.type() == GamepadChangeEvent::TGamepadRemoved) {

--- a/dom/gamepad/moz.build
+++ b/dom/gamepad/moz.build
@@ -5,27 +5,31 @@
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 IPDL_SOURCES += [
     'ipc/GamepadEventTypes.ipdlh',
     'ipc/PGamepadEventChannel.ipdl',
     'ipc/PGamepadTestChannel.ipdl'
 ]
 
+EXPORTS.mozilla.dom += [
+    'ipc/GamepadMessageUtils.h',
+    'ipc/GamepadServiceType.h'
+]
+
 if CONFIG['MOZ_GAMEPAD']:
     EXPORTS.mozilla.dom += [
         'Gamepad.h',
         'GamepadButton.h',
         'GamepadManager.h',
         'GamepadMonitoring.h',
         'GamepadPlatformService.h',
         'GamepadServiceTest.h',
         'ipc/GamepadEventChannelChild.h',
         'ipc/GamepadEventChannelParent.h',
-        'ipc/GamepadMessageUtils.h',
         'ipc/GamepadTestChannelChild.h',
         'ipc/GamepadTestChannelParent.h'
         ]
 
     UNIFIED_SOURCES = [
         'Gamepad.cpp',
         'GamepadButton.cpp',
         'GamepadManager.cpp',