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..9afdddcf8409b7f2ca2024029af42eb8632540f9 100644
--- a/third_party/WebKit/Source/core/input/MouseEventManager.h
+++ b/third_party/WebKit/Source/core/input/MouseEventManager.h
@@ -127,6 +127,7 @@ class CORE_EXPORT MouseEventManager final
   Node* GetNodeUnderMouse();
   bool IsMousePositionUnknown();
   IntPoint LastKnownMousePosition();

[bokan, 2017/06/15 17:40:13]

Should this eventually become a FloatPoint as well? i.e. is the only reason you
didn't make it so because it could affect current callers? If so, could you add
a comment/TODO?

[aelias_OOO_until_Jul13, 2017/06/15 22:19:54]

Yes.  I added a TODO.

+  FloatPoint LastKnownMousePositionGlobal();
 
   bool MousePressed();
   void SetMousePressed(bool);
@@ -211,8 +212,8 @@ 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.