Consuming a touch move prevents only the next scroll update.

content/browser/renderer_host/input/input_router_impl.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/input/input_router_impl.h"
 
 #include "base/auto_reset.h"
 #include "base/command_line.h"
 #include "base/metrics/histogram.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 91 matching lines @@
     case INPUT_EVENT_ACK_STATE_UNKNOWN: return "UNKNOWN";
     case INPUT_EVENT_ACK_STATE_CONSUMED: return "CONSUMED";
     case INPUT_EVENT_ACK_STATE_NOT_CONSUMED: return "NOT_CONSUMED";
     case INPUT_EVENT_ACK_STATE_NO_CONSUMER_EXISTS: return "NO_CONSUMER_EXISTS";
     case INPUT_EVENT_ACK_STATE_IGNORED: return "IGNORED";
   }
   DLOG(WARNING) << "Unhandled InputEventAckState in GetEventAckName.";
   return "";
 }
 
+TouchEventQueue::TouchScrollingMode GetTouchScrollingMode()
+{
+  std::string modeString = CommandLine::ForCurrentProcess()->
+      GetSwitchValueASCII(switches::kTouchScrollingMode);
+  if (modeString == switches::kTouchScrollingModeSyncTouchmove)
+    return TouchEventQueue::TOUCH_SCROLLING_MODE_SYNC_TOUCHMOVE;
+  if (modeString == switches::kTouchScrollingModeAbsorbTouchmove)
+    return TouchEventQueue::TOUCH_SCROLLING_MODE_ABSORB_TOUCHMOVE;
+  if (modeString != "" &&
+      modeString != switches::kTouchScrollingModeTouchcancel)
+    LOG(ERROR) << "Invalid --touch-scrolling-mode option: " << modeString;
+  return TouchEventQueue::TOUCH_SCROLLING_MODE_DEFAULT;
+}
+
 } // namespace
 
 InputRouterImpl::InputRouterImpl(IPC::Sender* sender,
                                  InputRouterClient* client,
                                  InputAckHandler* ack_handler,
                                  int routing_id)
     : sender_(sender),
       client_(client),
       ack_handler_(ack_handler),
       routing_id_(routing_id),
       select_range_pending_(false),
       move_caret_pending_(false),
       mouse_move_pending_(false),
       mouse_wheel_pending_(false),
       touch_ack_timeout_enabled_(false),
       touch_ack_timeout_delay_ms_(std::numeric_limits<size_t>::max()),
       current_ack_source_(ACK_SOURCE_NONE),
       gesture_event_queue_(new GestureEventQueue(this, this)) {
   DCHECK(sender);
   DCHECK(client);
   DCHECK(ack_handler);
-  touch_event_queue_.reset(new TouchEventQueue(this));
+  touch_event_queue_.reset(new TouchEventQueue(this, GetTouchScrollingMode()));
   touch_ack_timeout_enabled_ =
       GetTouchAckTimeoutDelayMs(&touch_ack_timeout_delay_ms_);
   touch_event_queue_->SetAckTimeoutEnabled(touch_ack_timeout_enabled_,
                                            touch_ack_timeout_delay_ms_);
 
   double touch_move_slop_suppression_length_dips = 0;
   if (GetTouchMoveSlopSuppressionLengthDips(
           &touch_move_slop_suppression_length_dips)) {
     touch_event_queue_->SetTouchMoveSlopSuppressionEnabled(
         true, touch_move_slop_suppression_length_dips);
@@ skipping 177 matching lines @@
 }
 
 void InputRouterImpl::OnTouchEventAck(const TouchEventWithLatencyInfo& event,
                                       InputEventAckState ack_result) {
   ack_handler_->OnTouchEventAck(event, ack_result);
 }
 
 void InputRouterImpl::OnGestureEventAck(
     const GestureEventWithLatencyInfo& event,
     InputEventAckState ack_result) {
+  touch_event_queue_->OnGestureEventAck(event, ack_result);
   ProcessAckForOverscroll(event.event, ack_result);
   ack_handler_->OnGestureEventAck(event, ack_result);
 }
 
 bool InputRouterImpl::SendSelectRange(scoped_ptr<IPC::Message> message) {
   DCHECK(message->type() == InputMsg_SelectRange::ID);
   if (select_range_pending_) {
     next_selection_range_ = message.Pass();
     return true;
   }
@@ skipping 408 matching lines @@
       break;
   }
 }
 
 bool InputRouterImpl::IsInOverscrollGesture() const {
   OverscrollController* controller = client_->GetOverscrollController();
   return controller && controller->overscroll_mode() != OVERSCROLL_NONE;
 }
 
 }  // namespace content