Wheel scroll latching enabled behind flag.

content/browser/renderer_host/input/mouse_wheel_event_queue.cc

Index: content/browser/renderer_host/input/mouse_wheel_event_queue.cc
diff --git a/content/browser/renderer_host/input/mouse_wheel_event_queue.cc b/content/browser/renderer_host/input/mouse_wheel_event_queue.cc
index d1d3bc22276279290e8cde1271e27591b76b26e3..60d187dc628995eb5a972fbfcfd563615d768e1d 100644
--- a/content/browser/renderer_host/input/mouse_wheel_event_queue.cc
+++ b/content/browser/renderer_host/input/mouse_wheel_event_queue.cc
@@ -34,13 +34,15 @@ class QueuedWebMouseWheelEvent : public MouseWheelEventWithLatencyInfo {
 };
 
 MouseWheelEventQueue::MouseWheelEventQueue(MouseWheelEventQueueClient* client,
-                                           int64_t scroll_transaction_ms)
+                                           bool enable_scroll_latching)
     : client_(client),
       needs_scroll_begin_(true),
       needs_scroll_end_(false),
-      scroll_transaction_ms_(scroll_transaction_ms),
+      enable_scroll_latching_(enable_scroll_latching),

[tdresser, 2016/08/12 13:28:32]

Do we need a local variable here? Or can we just assign scroll_transaction_ms_
based on the value of the constructor parameter?

[sahel, 2016/08/12 15:45:28]

For now the boolean variable is only used to set the scroll_transaction_ms_, but
we will need the boolean value to avoid sending the synthesized scroll begins
and ends for every update, when we have the phase info. 

       scrolling_device_(blink::WebGestureDeviceUninitialized) {
   DCHECK(client);
+  scroll_transaction_ms_ =
+      enable_scroll_latching_ ? kDefaultWheelScrollLatchingTransactionMs : 0;
 }
 
 MouseWheelEventQueue::~MouseWheelEventQueue() {