--- a/dom/gamepad/Gamepad.cpp
+++ b/dom/gamepad/Gamepad.cpp
@@ -102,16 +102,22 @@ Gamepad::SetAxis(uint32_t aAxis, double 
 void
 Gamepad::SetPose(const GamepadPoseState& aPose)
 {
   mPose->SetPoseState(aPose);
   UpdateTimestamp();
 }
 
 void
+Gamepad::SetHand(GamepadHand aHand)
+{
+  mHand = aHand;
+}
+
+void
 Gamepad::SyncState(Gamepad* aOther)
 {
   const char* kGamepadExtEnabledPref = "dom.gamepad.extensions.enabled";
 
   if (mButtons.Length() != aOther->mButtons.Length() ||
       mAxes.Length() != aOther->mAxes.Length()) {
     return;
   }

--- a/dom/gamepad/Gamepad.h
+++ b/dom/gamepad/Gamepad.h
@@ -51,16 +51,17 @@ public:
   NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(Gamepad)
 
   void SetConnected(bool aConnected);
   void SetButton(uint32_t aButton, bool aPressed,
                  bool aTouched, double aValue);
   void SetAxis(uint32_t aAxis, double aValue);
   void SetIndex(uint32_t aIndex);
   void SetPose(const GamepadPoseState& aPose);
+  void SetHand(GamepadHand aHand);
 
   // Make the state of this gamepad equivalent to other.
   void SyncState(Gamepad* aOther);
 
   // Return a new Gamepad containing the same data as this object,
   // parented to aParent.
   already_AddRefed<Gamepad> Clone(nsISupports* aParent);