diff --git a/widget/InputData.cpp b/widget/InputData.cpp
index 33a5e6c2be54..2c2e76fde086 100644
--- a/widget/InputData.cpp
+++ b/widget/InputData.cpp
@@ -28,6 +28,49 @@ already_AddRefed<Touch> SingleTouchData::ToNewDOMTouch() const
   return touch.forget();
 }
 
+MouseInput::MouseInput(const WidgetMouseEventBase& aMouseEvent)
+  : InputData(MOUSE_INPUT, aMouseEvent.time, aMouseEvent.timeStamp,
+              aMouseEvent.modifiers)
+{
+  MOZ_ASSERT(NS_IsMainThread(),
+             "Can only copy from WidgetTouchEvent on main thread");
+
+  mButtonType = NONE;
+
+  switch (aMouseEvent.button) {
+    case WidgetMouseEventBase::eLeftButton:
+      mButtonType = MouseInput::LEFT_BUTTON;
+      break;
+    case WidgetMouseEventBase::eMiddleButton:
+      mButtonType = MouseInput::MIDDLE_BUTTON;
+      break;
+    case WidgetMouseEventBase::eRightButton:
+      mButtonType = MouseInput::RIGHT_BUTTON;
+      break;
+  }
+
+  switch (aMouseEvent.mMessage) {
+    case eMouseMove:
+      mType = MOUSE_MOVE;
+      break;
+    case eMouseUp:
+      mType = MOUSE_UP;
+      break;
+    case eMouseDown:
+      mType = MOUSE_DOWN;
+      break;
+    case eDragStart:
+      mType = MOUSE_DRAG_START;
+      break;
+    case eDragEnd:
+      mType = MOUSE_DRAG_END;
+      break;
+    default:
+      MOZ_ASSERT_UNREACHABLE("Mouse event type not supported");
+      break;
+  }
+}
+
 MultiTouchInput::MultiTouchInput(const WidgetTouchEvent& aTouchEvent)
   : InputData(MULTITOUCH_INPUT, aTouchEvent.time, aTouchEvent.timeStamp,
               aTouchEvent.modifiers)
diff --git a/widget/InputData.h b/widget/InputData.h
index 637ffadacbed..c6fa6d093f35 100644
--- a/widget/InputData.h
+++ b/widget/InputData.h
@@ -30,6 +30,7 @@ class Matrix4x4;
 enum InputType
 {
   MULTITOUCH_INPUT,
+  MOUSE_INPUT,
   PANGESTURE_INPUT,
   PINCHGESTURE_INPUT,
   TAPGESTURE_INPUT,
@@ -37,6 +38,7 @@ enum InputType
 };
 
 class MultiTouchInput;
+class MouseInput;
 class PanGestureInput;
 class PinchGestureInput;
 class TapGestureInput;
@@ -76,6 +78,7 @@ public:
   Modifiers modifiers;
 
   INPUTDATA_AS_CHILD_TYPE(MultiTouchInput, MULTITOUCH_INPUT)
+  INPUTDATA_AS_CHILD_TYPE(MouseInput, MOUSE_INPUT)
   INPUTDATA_AS_CHILD_TYPE(PanGestureInput, PANGESTURE_INPUT)
   INPUTDATA_AS_CHILD_TYPE(PinchGestureInput, PINCHGESTURE_INPUT)
   INPUTDATA_AS_CHILD_TYPE(TapGestureInput, TAPGESTURE_INPUT)
@@ -245,6 +248,47 @@ public:
   nsTArray<SingleTouchData> mTouches;
 };
 
+class MouseInput : public InputData
+{
+public:
+  enum MouseType
+  {
+    MOUSE_MOVE,
+    MOUSE_DOWN,
+    MOUSE_UP,
+    MOUSE_DRAG_START,
+    MOUSE_DRAG_END,
+  };
+
+  enum ButtonType
+  {
+    LEFT_BUTTON,
+    MIDDLE_BUTTON,
+    RIGHT_BUTTON,
+    NONE
+  };
+
+  MouseInput(MouseType aType, ButtonType aButtonType, uint32_t aTime,
+             TimeStamp aTimeStamp, Modifiers aModifiers)
+    : InputData(MOUSE_INPUT, aTime, aTimeStamp, aModifiers)
+    , mType(aType)
+    , mButtonType(aButtonType)
+  {}
+
+  MouseInput()
+    : InputData(MOUSE_INPUT)
+  {}
+
+  explicit MouseInput(const WidgetMouseEventBase& aMouseEvent);
+
+  bool IsLeftButton() const { return mButtonType == LEFT_BUTTON; }
+
+  MouseType mType;
+  ButtonType mButtonType;
+  ScreenPoint mOrigin;
+  ParentLayerPoint mLocalOrigin;
+};
+
 /**
  * Encapsulation class for pan events, can be used off-main-thread.
  * These events are currently only used for scrolling on desktop.