Coalesce async touch move events until the ack back from render

content/renderer/render_widget.cc

 // Copyright (c) 2012 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/renderer/render_widget.h"
 
 #include "base/auto_reset.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/logging.h"
@@ skipping 1220 matching lines @@
           total_input_handling_time_this_frame_.InMicroseconds() >
           kInputHandlingTimeThrottlingThresholdMicroseconds;
   }
 
   TRACE_EVENT_SYNTHETIC_DELAY_END("blink.HandleInputEvent");
 
   // Note that we can't use handling_event_type_ here since it will be overriden
   // by reentrant calls for events after the paused one.
   bool no_ack = ignore_ack_for_mouse_move_from_debugger_ &&
       input_event->type == WebInputEvent::MouseMove;
-  if (!WebInputEventTraits::IgnoresAckDisposition(*input_event) && !no_ack) {
-    InputHostMsg_HandleInputEvent_ACK_Params ack;
-    ack.type = input_event->type;
-    ack.state = ack_result;
-    ack.latency = swap_latency_info;
+  if (WebInputEventTraits::WillReceiveAckFromRenderer(*input_event) &&
+      !no_ack) {
+    InputEventAck ack(input_event->type, ack_result, swap_latency_info,
+                      WebInputEventTraits::GetUniqueTouchEventId(*input_event));
     scoped_ptr<IPC::Message> response(
         new InputHostMsg_HandleInputEvent_ACK(routing_id_, ack));
     if (rate_limiting_wanted && frame_pending && !is_hidden_) {
       // We want to rate limit the input events in this case, so we'll wait for
       // painting to finish before ACKing this message.
       TRACE_EVENT_INSTANT0("renderer",
         "RenderWidget::OnHandleInputEvent ack throttled",
         TRACE_EVENT_SCOPE_THREAD);
       if (pending_input_event_ack_) {
         TRACE_EVENT_ASYNC_END0("input", "RenderWidget::ThrottledInputEventAck",
@@ skipping 525 matching lines @@
 #else
   return !!webwidget_;
 #endif
 }
 
 bool RenderWidget::SendAckForMouseMoveFromDebugger() {
   if (handling_event_type_ == WebInputEvent::MouseMove) {
     // If we pause multiple times during a single mouse move event, we should
     // only send ACK once.
     if (!ignore_ack_for_mouse_move_from_debugger_) {
-      InputHostMsg_HandleInputEvent_ACK_Params ack;
-      ack.type = handling_event_type_;
-      ack.state = INPUT_EVENT_ACK_STATE_CONSUMED;
+      InputEventAck ack(handling_event_type_, INPUT_EVENT_ACK_STATE_CONSUMED);
       Send(new InputHostMsg_HandleInputEvent_ACK(routing_id_, ack));
       return true;
     }
   }
   return false;
 }
 
 void RenderWidget::IgnoreAckForMouseMoveFromDebugger() {
   ignore_ack_for_mouse_move_from_debugger_ = true;
 }
@@ skipping 662 matching lines @@
 void RenderWidget::RegisterVideoHoleFrame(RenderFrameImpl* frame) {
   video_hole_frames_.AddObserver(frame);
 }
 
 void RenderWidget::UnregisterVideoHoleFrame(RenderFrameImpl* frame) {
   video_hole_frames_.RemoveObserver(frame);
 }
 #endif  // defined(VIDEO_HOLE)
 
 }  // namespace content