Move middle-click autoscroll to synthetic fling.

third_party/WebKit/public/web/WebWidgetClient.h

Index: third_party/WebKit/public/web/WebWidgetClient.h
diff --git a/third_party/WebKit/public/web/WebWidgetClient.h b/third_party/WebKit/public/web/WebWidgetClient.h
index c948511f5977f57284746f795a5ef1827f0d1f99..cd56c112ba95cfd8cc42faacbf3cdf0677a9ea89 100644
--- a/third_party/WebKit/public/web/WebWidgetClient.h
+++ b/third_party/WebKit/public/web/WebWidgetClient.h
@@ -84,6 +84,10 @@ class WebWidgetClient {
   // Called when the cursor for the widget changes.
   virtual void DidChangeCursor(const WebCursorInfo&) {}
 
+  virtual void AutoscrollStart(const WebFloatPoint&) {}
+  virtual void AutoscrollFling(const WebFloatSize& velocity) {}
+  virtual void AutoscrollEnd() {}
+
   // Called when the widget should be closed.  WebWidget::close() should
   // be called asynchronously as a result of this notification.
   virtual void CloseWidgetSoon() {}