Coalesce async touch move events until the ack back from render

content/browser/renderer_host/render_widget_host_unittest.cc

Index: content/browser/renderer_host/render_widget_host_unittest.cc
diff --git a/content/browser/renderer_host/render_widget_host_unittest.cc b/content/browser/renderer_host/render_widget_host_unittest.cc
index 46acbd1dbae6d48581ac9393358222dd4d686b81..06ace4d38a0ed567991cca523b9ecc9381aef819 100644
--- a/content/browser/renderer_host/render_widget_host_unittest.cc
+++ b/content/browser/renderer_host/render_widget_host_unittest.cc
@@ -459,12 +459,24 @@ class RenderWidgetHostTest : public testing::Test {
 
   void SendInputEventACK(WebInputEvent::Type type,
                          InputEventAckState ack_result) {
-    InputHostMsg_HandleInputEvent_ACK_Params ack;
-    ack.type = type;
-    ack.state = ack_result;
+    DCHECK(!WebInputEvent::isTouchEventType(type));
+    InputEventAck ack(type, ack_result);
     host_->OnMessageReceived(InputHostMsg_HandleInputEvent_ACK(0, ack));
   }
 
+  uint32 LastSentEventID() {
+    uint32 last_sent_event_id = 0;
+    size_t count = process_->sink().message_count();
+    DCHECK_GT(count, 0U);
+    for (size_t i = 0; i < count; ++i) {
+      const WebInputEvent* input_event =
+          GetInputEventFromMessage(*process_->sink().GetMessageAt(i));
+      last_sent_event_id =
+          WebInputEventTraits::GetUniqueTouchEventId(*input_event);
+    }
+    return last_sent_event_id;
+  }
+
   double GetNextSimulatedEventTimeSeconds() {
     last_simulated_event_time_seconds_ += simulated_event_time_delta_seconds_;
     return last_simulated_event_time_seconds_;
@@ -1436,9 +1448,11 @@ TEST_F(RenderWidgetHostTest, InputEventRWHLatencyComponent) {
   // Tests RWHI::ForwardTouchEventWithLatencyInfo().
   PressTouchPoint(0, 1);
   SendTouchEvent();
+  InputEventAck ack(WebInputEvent::TouchStart, INPUT_EVENT_ACK_STATE_CONSUMED);
+  ack.unique_touch_event_id = LastSentEventID();
+  host_->OnMessageReceived(InputHostMsg_HandleInputEvent_ACK(0, ack));
   CheckLatencyInfoComponentInMessage(
       process_, GetLatencyComponentId(), WebInputEvent::TouchStart);
-  SendInputEventACK(WebInputEvent::TouchStart, INPUT_EVENT_ACK_STATE_CONSUMED);
 }
 
 TEST_F(RenderWidgetHostTest, RendererExitedResetsInputRouter) {