Remove touch-scrolling-mode flag

content/browser/renderer_host/input/touch_event_queue.cc

Index: content/browser/renderer_host/input/touch_event_queue.cc
diff --git a/content/browser/renderer_host/input/touch_event_queue.cc b/content/browser/renderer_host/input/touch_event_queue.cc
index f66493ac92eed17dfd818d83faf9bb2d8d7693ea..d7d54d4166169446ec78b79f790a08febe7103a4 100644
--- a/content/browser/renderer_host/input/touch_event_queue.cc
+++ b/content/browser/renderer_host/input/touch_event_queue.cc
@@ -343,8 +343,7 @@ class CoalescedWebTouchEvent {
 };
 
 TouchEventQueue::Config::Config()
-    : touch_scrolling_mode(TOUCH_SCROLLING_MODE_DEFAULT),
-      touch_ack_timeout_delay(base::TimeDelta::FromMilliseconds(200)),
+    : touch_ack_timeout_delay(base::TimeDelta::FromMilliseconds(200)),
       touch_ack_timeout_supported(false) {
 }
 
@@ -357,8 +356,7 @@ TouchEventQueue::TouchEventQueue(TouchEventQueueClient* client,
       drop_remaining_touches_in_sequence_(false),
       touchmove_slop_suppressor_(new TouchMoveSlopSuppressor),
       send_touch_events_async_(false),
-      last_sent_touch_timestamp_sec_(0),
-      touch_scrolling_mode_(config.touch_scrolling_mode) {
+      last_sent_touch_timestamp_sec_(0) {
   DCHECK(client);
   if (config.touch_ack_timeout_supported) {
     timeout_handler_.reset(
@@ -527,8 +525,7 @@ void TouchEventQueue::OnGestureScrollEvent(
       DCHECK(!touchmove_slop_suppressor_->suppressing_touchmoves())
           <<  "A touch handler should be offered a touchmove before scrolling.";
     }
-    if (touch_scrolling_mode_ == TOUCH_SCROLLING_MODE_ASYNC_TOUCHMOVE &&
-        !drop_remaining_touches_in_sequence_ &&
+    if (!drop_remaining_touches_in_sequence_ &&
         touch_consumer_states_.is_empty()) {
       // If no touch points have a consumer, prevent all subsequent touch events
       // received during the scroll from reaching the renderer. This ensures
@@ -538,8 +535,7 @@ void TouchEventQueue::OnGestureScrollEvent(
       drop_remaining_touches_in_sequence_ = true;
     }
 
-    if (touch_scrolling_mode_ == TOUCH_SCROLLING_MODE_ASYNC_TOUCHMOVE)
-      pending_async_touchmove_.reset();
+    pending_async_touchmove_.reset();
 
     return;
   }
@@ -547,41 +543,12 @@ void TouchEventQueue::OnGestureScrollEvent(
   if (gesture_event.event.type != blink::WebInputEvent::GestureScrollUpdate)

[jdduke (slow), 2015/01/30 00:12:56]

I guess we might as well consolidate this if with the assignment (invert the
condition), also in the |OnGestureEventAck| below.

[lanwei, 2015/02/03 20:44:32]

Done.

     return;
 
-  if (touch_scrolling_mode_ == TOUCH_SCROLLING_MODE_ASYNC_TOUCHMOVE)
-    send_touch_events_async_ = true;
-
-  if (touch_scrolling_mode_ != TOUCH_SCROLLING_MODE_TOUCHCANCEL)
-    return;
-
-  // We assume that scroll events are generated synchronously from
-  // dispatching a touch event ack. This allows us to generate a synthetic
-  // cancel event that has the same touch ids as the touch event that
-  // is being acked. Otherwise, we don't perform the touch-cancel optimization.
-  if (!dispatching_touch_ack_)
-    return;
-
-  if (drop_remaining_touches_in_sequence_)
-    return;
-
-  drop_remaining_touches_in_sequence_ = true;
-
-  // Fake a TouchCancel to cancel the touch points of the touch event
-  // that is currently being acked.
-  // Note: |dispatching_touch_ack_| is non-null when we reach here, meaning we
-  // are in the scope of PopTouchEventToClient() and that no touch event
-  // in the queue is waiting for ack from renderer. So we can just insert
-  // the touch cancel at the beginning of the queue.
-  touch_queue_.push_front(new CoalescedWebTouchEvent(
-      ObtainCancelEventForTouchEvent(
-          dispatching_touch_ack_->coalesced_event()), true));
+  send_touch_events_async_ = true;
 }
 
 void TouchEventQueue::OnGestureEventAck(
     const GestureEventWithLatencyInfo& event,
     InputEventAckState ack_result) {
-  if (touch_scrolling_mode_ != TOUCH_SCROLLING_MODE_ASYNC_TOUCHMOVE)
-    return;
-
   if (event.event.type != blink::WebInputEvent::GestureScrollUpdate)
     return;
 
@@ -732,8 +699,7 @@ void TouchEventQueue::UpdateTouchConsumerStates(const WebTouchEvent& event,
         touch_consumer_states_.clear_bit(point.id);
     }
   } else if (event.type == WebInputEvent::TouchStart) {
-    if (touch_scrolling_mode_ == TOUCH_SCROLLING_MODE_ASYNC_TOUCHMOVE &&
-        ack_result == INPUT_EVENT_ACK_STATE_CONSUMED) {
+    if (ack_result == INPUT_EVENT_ACK_STATE_CONSUMED) {

[jdduke (slow), 2015/01/30 00:12:56]

Nit: Looks like we can remove this one-line if brace.

[lanwei, 2015/02/03 20:44:32]

Done.

       send_touch_events_async_ = false;
     }
     for (unsigned i = 0; i < event.touchesLength; ++i) {