Wheel scroll latching enabled behind flag.

content/browser/renderer_host/input/mouse_wheel_event_queue.h

Index: content/browser/renderer_host/input/mouse_wheel_event_queue.h
diff --git a/content/browser/renderer_host/input/mouse_wheel_event_queue.h b/content/browser/renderer_host/input/mouse_wheel_event_queue.h
index a2722310b74b68c0c7e5c3f261851c65a969432d..234455ac5b7381611ecb7282301ce2e6ae9f9992 100644
--- a/content/browser/renderer_host/input/mouse_wheel_event_queue.h
+++ b/content/browser/renderer_host/input/mouse_wheel_event_queue.h
@@ -19,7 +19,7 @@ namespace content {
 // ScrollUpdate was sent for wheel based gesture scrolls.
 // Set the default wheel transaction to 0ms until
 // crbug.com/526463 is fully implemented.
-const int64_t kDefaultWheelScrollTransactionMs = 0;  // 100;
+int64_t kDefaultWheelScrollTransactionMs;
 
 class QueuedWebMouseWheelEvent;
 
@@ -100,6 +100,8 @@ class CONTENT_EXPORT MouseWheelEventQueue {
   int64_t scroll_transaction_ms_;
   blink::WebGestureDevice scrolling_device_;
 
+  bool touchpad_scroll_latching_;
+
   DISALLOW_COPY_AND_ASSIGN(MouseWheelEventQueue);
 };