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..a3cecb7a55897ae30b030d608e4c8dc0673b9bab 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 +19,8 @@ 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;
+const int64_t kDefaultWheelScrollTransactionMs = 0;
+const int64_t kDefaultWheelScrollLatchingTransactionMs = 100;
 
 class QueuedWebMouseWheelEvent;
 
@@ -100,6 +101,9 @@ class CONTENT_EXPORT MouseWheelEventQueue {
   int64_t scroll_transaction_ms_;
   blink::WebGestureDevice scrolling_device_;
 
+  // True if the touchpad scroll latching is enabled.
+  bool touchpad_scroll_latching_;
+
   DISALLOW_COPY_AND_ASSIGN(MouseWheelEventQueue);
 };