--- a/dom/system/GamepadService.cpp
+++ b/dom/system/GamepadService.cpp
@@ -1,14 +1,15 @@
 /* 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/Hal.h"
 #include "mozilla/ClearOnShutdown.h"
+#include "mozilla/Preferences.h"
 #include "mozilla/StaticPtr.h"
 
 #include "GamepadService.h"
 #include "nsAutoPtr.h"
 #include "nsIDOMEvent.h"
 #include "nsIDOMDocument.h"
 #include "nsDOMGamepad.h"
 #include "nsIDOMGamepadButtonEvent.h"
@@ -24,64 +25,67 @@
 #include "mozilla/Services.h"
 
 #include <cstddef>
 
 namespace mozilla {
 namespace dom {
 
 namespace {
+const char* kGamepadEnabledPref = "dom.gamepad.enabled";
 // Amount of time to wait before cleaning up gamepad resources
 // when no pages are listening for events.
 const int kCleanupDelayMS = 2000;
 const nsTArray<nsRefPtr<nsGlobalWindow> >::index_type NoIndex =
     nsTArray<nsRefPtr<nsGlobalWindow> >::NoIndex;
 
 StaticRefPtr<GamepadService> gGamepadServiceSingleton;
 
 } // namespace
 
 bool GamepadService::sShutdown = false;
 
-NS_IMPL_ISUPPORTS0(GamepadService)
+NS_IMPL_ISUPPORTS1(GamepadService, nsIObserver)
 
 GamepadService::GamepadService()
   : mStarted(false),
     mShuttingDown(false)
 {
+  mEnabled = Preferences::GetBool(kGamepadEnabledPref, false);
   nsCOMPtr<nsIObserverService> observerService =
     mozilla::services::GetObserverService();
   observerService->AddObserver(this,
                                NS_XPCOM_WILL_SHUTDOWN_OBSERVER_ID,
                                false);
 }
 
 NS_IMETHODIMP
 GamepadService::Observe(nsISupports* aSubject,
                         const char* aTopic,
                         const PRUnichar* aData)
 {
   nsCOMPtr<nsIObserverService> observerService =
     mozilla::services::GetObserverService();
-  nsCOMPtr<nsIObserver> observer = do_QueryInterface(this);
-  observerService->RemoveObserver(observer, NS_XPCOM_WILL_SHUTDOWN_OBSERVER_ID);
+  observerService->RemoveObserver(this, NS_XPCOM_WILL_SHUTDOWN_OBSERVER_ID);
 
   BeginShutdown();
   return NS_OK;
 }
 
 void
 GamepadService::BeginShutdown()
 {
   mShuttingDown = true;
   if (mTimer) {
     mTimer->Cancel();
   }
-  mozilla::hal::StopMonitoringGamepadStatus();
-  mStarted = false;
+  if (mStarted) {
+    mozilla::hal::StopMonitoringGamepadStatus();
+    mStarted = false;
+  }
   // Don't let windows call back to unregister during shutdown
   for (uint32_t i = 0; i < mListeners.Length(); i++) {
     mListeners[i]->SetHasGamepadEventListener(false);
   }
   mListeners.Clear();
   mGamepads.Clear();
   sShutdown = true;
 }
@@ -92,17 +96,17 @@ GamepadService::AddListener(nsGlobalWind
   if (mShuttingDown) {
     return;
   }
 
   if (mListeners.IndexOf(aWindow) != NoIndex) {
     return; // already exists
   }
 
-  if (!mStarted) {
+  if (!mStarted && mEnabled) {
     mozilla::hal::StartMonitoringGamepadStatus();
     mStarted = true;
   }
 
   mListeners.AppendElement(aWindow);
 }
 
 void
@@ -115,17 +119,17 @@ GamepadService::RemoveListener(nsGlobalW
   }
 
   if (mListeners.IndexOf(aWindow) == NoIndex) {
     return; // doesn't exist
   }
 
   mListeners.RemoveElement(aWindow);
 
-  if (mListeners.Length() == 0 && !mShuttingDown) {
+  if (mListeners.Length() == 0 && !mShuttingDown && mStarted) {
     StartCleanupTimer();
   }
 }
 
 uint32_t
 GamepadService::AddGamepad(const char* aId,
                            uint32_t aNumButtons,
                            uint32_t aNumAxes)
@@ -366,17 +370,17 @@ GamepadService::FireConnectionEvent(Even
   je->SetTrusted(true);
 
   aTarget->DispatchEvent(event, &defaultActionEnabled);
 }
 
 void
 GamepadService::SyncGamepadState(uint32_t aIndex, nsDOMGamepad* aGamepad)
 {
-  if (mShuttingDown || aIndex > mGamepads.Length()) {
+  if (mShuttingDown || !mEnabled || aIndex > mGamepads.Length()) {
     return;
   }
 
   aGamepad->SyncState(mGamepads[aIndex]);
 }
 
 // static
 already_AddRefed<GamepadService>

--- a/dom/system/GamepadService.h
+++ b/dom/system/GamepadService.h
@@ -65,16 +65,18 @@ class GamepadService : public nsIObserve
   void FireButtonEvent(EventTarget* aTarget,
                        nsDOMGamepad* aGamepad,
                        uint32_t aButton,
                        double aValue);
   void FireConnectionEvent(EventTarget* aTarget,
                            nsDOMGamepad* aGamepad,
                            bool aConnected);
 
+  // true if this feature is enabled in preferences
+  bool mEnabled;
   // true if the platform-specific backend has started work
   bool mStarted;
   // true when shutdown has begun
   bool mShuttingDown;
 
  private:
   // Returns true if we have already sent data from this gamepad
   // to this window. This should only return true if the user

--- a/dom/tests/mochitest/gamepad/Makefile.in
+++ b/dom/tests/mochitest/gamepad/Makefile.in
@@ -6,17 +6,16 @@ DEPTH		= ../../../..
 topsrcdir	= @top_srcdir@
 srcdir		= @srcdir@
 VPATH		= @srcdir@
 relativesrcdir	= dom/tests/mochitest/gamepad
 
 include $(DEPTH)/config/autoconf.mk
 
 MOCHITEST_FILES = \
-  test_gamepad_basic.html \
   test_gamepad.html \
   test_gamepad_frame_state_sync.html \
   gamepad_frame_state.html \
   test_gamepad_hidden_frame.html \
   gamepad_frame.html \
   mock_gamepad.js \
   $(NULL)
 

deleted file mode 100644
--- a/dom/tests/mochitest/gamepad/test_gamepad_basic.html
+++ /dev/null
@@ -1,22 +0,0 @@
-<!-- Any copyright is dedicated to the Public Domain.
-   - http://creativecommons.org/publicdomain/zero/1.0/ -->
-<!DOCTYPE HTML>
-<html>
-<head>
-  <title>Test gamepad  </title>
-  <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
-  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
-</head>
-<body>
-<script class="testbody" type="text/javascript">
-
-// Not much we can test here, but this is enough to get the
-// gamepad service up and running, which should test that it
-// doesn't leak anything.
-window.addEventListener("gamepadconnected", function() {});
-SimpleTest.ok(true, "dummy check");
-
-</script>
-</body>
-</html>
-

--- a/dom/webidl/Gamepad.webidl
+++ b/dom/webidl/Gamepad.webidl
@@ -1,14 +1,16 @@
+/* -*- 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/. */
 
 interface nsIVariant;
 
+[Pref="dom.gamepad.enabled"]
 interface Gamepad {
   /**
    * An identifier, unique per type of device.
    */
   readonly attribute DOMString id;
 
   /**
    * The game port index for the device. Unique per device

--- a/dom/webidl/GamepadAxisMoveEvent.webidl
+++ b/dom/webidl/GamepadAxisMoveEvent.webidl
@@ -1,15 +1,17 @@
 /* -*- 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/.
  */
 
-[Constructor(DOMString type, optional GamepadAxisMoveEventInit eventInitDict), HeaderFile="GeneratedEventClasses.h"]
+[Pref="dom.gamepad.enabled",
+ Constructor(DOMString type, optional GamepadAxisMoveEventInit eventInitDict),
+ HeaderFile="GeneratedEventClasses.h"]
 interface GamepadAxisMoveEvent : GamepadEvent
 {
   readonly attribute unsigned long axis;
   readonly attribute double value;
 };
 
 dictionary GamepadAxisMoveEventInit : GamepadEventInit
 {

--- a/dom/webidl/GamepadButtonEvent.webidl
+++ b/dom/webidl/GamepadButtonEvent.webidl
@@ -1,15 +1,17 @@
 /* -*- 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/.
  */
 
-[Constructor(DOMString type, optional GamepadButtonEventInit eventInitDict), HeaderFile="GeneratedEventClasses.h"]
+[Pref="dom.gamepad.enabled",
+ Constructor(DOMString type, optional GamepadButtonEventInit eventInitDict),
+ HeaderFile="GeneratedEventClasses.h"]
 interface GamepadButtonEvent : GamepadEvent
 {
   readonly attribute unsigned long button;
 };
 
 dictionary GamepadButtonEventInit : GamepadEventInit
 {
   unsigned long button = 0;

--- a/dom/webidl/GamepadEvent.webidl
+++ b/dom/webidl/GamepadEvent.webidl
@@ -1,15 +1,17 @@
 /* -*- 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/.
  */
 
-[Constructor(DOMString type, optional GamepadEventInit eventInitDict), HeaderFile="GeneratedEventClasses.h"]
+[Pref="dom.gamepad.enabled",
+ Constructor(DOMString type, optional GamepadEventInit eventInitDict),
+ HeaderFile="GeneratedEventClasses.h"]
 interface GamepadEvent : Event
 {
   readonly attribute Gamepad? gamepad;
 };
 
 dictionary GamepadEventInit : EventInit
 {
   Gamepad? gamepad = null;

--- a/modules/libpref/src/init/all.js
+++ b/modules/libpref/src/init/all.js
@@ -84,16 +84,23 @@ pref("dom.indexedDB.warningQuota", 50);
 // Whether or not Web Workers are enabled.
 pref("dom.workers.enabled", true);
 // The number of workers per domain allowed to run concurrently.
 pref("dom.workers.maxPerDomain", 20);
 
 // Whether nonzero values can be returned from performance.timing.*
 pref("dom.enable_performance", true);
 
+// Whether the Gamepad API is enabled
+#ifdef RELEASE_BUILD
+pref("dom.gamepad.enabled", false);
+#else
+pref("dom.gamepad.enabled", true);
+#endif
+
 // Fastback caching - if this pref is negative, then we calculate the number
 // of content viewers to cache based on the amount of available memory.
 pref("browser.sessionhistory.max_total_viewers", -1);
 
 pref("ui.use_native_colors", true);
 pref("ui.click_hold_context_menus", false);
 pref("browser.display.use_document_fonts",  1);  // 0 = never, 1 = quick, 2 = always
 pref("browser.display.use_document_colors", true);

--- a/testing/profiles/prefs_general.js
+++ b/testing/profiles/prefs_general.js
@@ -121,8 +121,11 @@ user_pref("dom.navigator-property.disabl
 user_pref("dom.global-constructor.disable.mozContact", false);
 
 // Enable mozSettings
 user_pref("dom.mozSettings.enabled", true);
 user_pref("dom.navigator-property.disable.mozSettings", false);
 
 // Make sure the disk cache doesn't get auto disabled
 user_pref("network.http.bypass-cachelock-threshold", 200000);
+
+// Enable Gamepad
+user_pref("dom.gamepad.enabled", true);