Move middle-click autoscroll to synthetic fling.

third_party/WebKit/Source/core/input/MouseEventManager.h

Index: third_party/WebKit/Source/core/input/MouseEventManager.h
diff --git a/third_party/WebKit/Source/core/input/MouseEventManager.h b/third_party/WebKit/Source/core/input/MouseEventManager.h
index b0086b088bed3bfce98394abd99f86fdb2ea930d..0a1f7b406524bfee617a789b74c6b476c1897754 100644
--- a/third_party/WebKit/Source/core/input/MouseEventManager.h
+++ b/third_party/WebKit/Source/core/input/MouseEventManager.h
@@ -126,7 +126,9 @@ class CORE_EXPORT MouseEventManager final
   // refactoring to be able to remove the dependency from EventHandler.
   Node* GetNodeUnderMouse();
   bool IsMousePositionUnknown();
+  // TODO(aelias): Make LastKnownMousePosition return FloatPoint.
   IntPoint LastKnownMousePosition();
+  FloatPoint LastKnownMousePositionGlobal();
 
   bool MousePressed();
   void SetMousePressed(bool);
@@ -211,8 +213,8 @@ class CORE_EXPORT MouseEventManager final
 
   // The last mouse movement position this frame has seen in root frame
   // coordinates.
-  IntPoint last_known_mouse_position_;
-  IntPoint last_known_mouse_global_position_;
+  FloatPoint last_known_mouse_position_;
+  FloatPoint last_known_mouse_global_position_;
 
   unsigned is_mouse_position_unknown_ : 1;
   // Current button-press state for mouse/mouse-like-stylus.