Coalesce async touch move events until the ack back from render

content/browser/renderer_host/render_widget_host_view_aura_unittest.cc

Index: content/browser/renderer_host/render_widget_host_view_aura_unittest.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_aura_unittest.cc b/content/browser/renderer_host/render_widget_host_view_aura_unittest.cc
index aba2b57322ef07d0fe0960cff38befe6ac9c07b5..b01be69dc65dd54589258de1cf815fc5fd13d052 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura_unittest.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura_unittest.cc
@@ -443,9 +443,17 @@ class RenderWidgetHostViewAuraTest : 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);
+    InputHostMsg_HandleInputEvent_ACK response(0, ack);
+    widget_host_->OnMessageReceived(response);
+  }
+
+  void SendTouchEventACK(WebInputEvent::Type type, uint32 event_id,
+      InputEventAckState ack_result) {
+    DCHECK(WebInputEvent::isTouchEventType(type));
+    InputEventAck ack(type, ack_result);
+    ack.unique_touch_event_id = event_id;
     InputHostMsg_HandleInputEvent_ACK response(0, ack);
     widget_host_->OnMessageReceived(response);
   }
@@ -466,10 +474,23 @@ class RenderWidgetHostViewAuraTest : public testing::Test {
       return;
     }
 
-    if (WebInputEventTraits::IgnoresAckDisposition(*get<0>(params)))
+    if (!WebInputEventTraits::WillReceiveAckFromRenderer(*get<0>(params)))
       return;
 
-    SendInputEventACK(get<0>(params)->type, ack_result);
+    SendTouchEventACK(get<0>(params)->type, LastSentEventID(), ack_result);
+  }
+
+  uint32 LastSentEventID() {
+    uint32 last_sent_event_id = 0;
+    size_t count = sink_->message_count();
+    DCHECK_GT(count, 0U);
+    for (size_t i = 0; i < count; ++i) {
+      const WebInputEvent* input_event =
+          GetInputEventFromMessage(*sink_->GetMessageAt(i));
+      last_sent_event_id =
+          WebInputEventTraits::GetUniqueTouchEventId(*input_event);
+    }
+    return last_sent_event_id;
   }
 
  protected:
@@ -1102,9 +1123,9 @@ TEST_F(RenderWidgetHostViewAuraTest, TouchEventState) {
   widget_host_->OnMessageReceived(ViewHostMsg_HasTouchEventHandlers(0, false));
 
   // Ack'ing the outstanding event should flush the pending touch queue.
-  InputHostMsg_HandleInputEvent_ACK_Params ack;
-  ack.type = blink::WebInputEvent::TouchStart;
-  ack.state = INPUT_EVENT_ACK_STATE_NO_CONSUMER_EXISTS;
+  InputEventAck ack(blink::WebInputEvent::TouchStart,
+                    INPUT_EVENT_ACK_STATE_NO_CONSUMER_EXISTS);
+  ack.unique_touch_event_id = press.unique_event_id();
   widget_host_->OnMessageReceived(InputHostMsg_HandleInputEvent_ACK(0, ack));
   EXPECT_EQ(0U, GetSentMessageCountAndResetSink());
 
@@ -2780,14 +2801,14 @@ TEST_F(RenderWidgetHostViewAuraOverscrollTest, OverscrollWithTouchEvents) {
 
   // The test sends an intermingled sequence of touch and gesture events.
   PressTouchPoint(0, 1);
-  SendInputEventACK(WebInputEvent::TouchStart,
+  SendTouchEventACK(WebInputEvent::TouchStart, LastSentEventID(),
                     INPUT_EVENT_ACK_STATE_NOT_CONSUMED);
   EXPECT_EQ(1U, GetSentMessageCountAndResetSink());
 
   MoveTouchPoint(0, 20, 5);
-  EXPECT_EQ(1U, GetSentMessageCountAndResetSink());
-  SendInputEventACK(WebInputEvent::TouchMove,
+  SendTouchEventACK(WebInputEvent::TouchMove, LastSentEventID(),
                     INPUT_EVENT_ACK_STATE_NOT_CONSUMED);
+  EXPECT_EQ(1U, GetSentMessageCountAndResetSink());
 
   EXPECT_EQ(OVERSCROLL_NONE, overscroll_mode());
   EXPECT_EQ(OVERSCROLL_NONE, overscroll_delegate()->current_mode());
@@ -3312,13 +3333,13 @@ TEST_F(RenderWidgetHostViewAuraTest, CorrectNumberOfAcksAreDispatched) {
       ui::ET_TOUCH_PRESSED, gfx::Point(30, 30), 0, ui::EventTimeForNow());
 
   view_->OnTouchEvent(&press1);
-  SendInputEventACK(blink::WebInputEvent::TouchStart,
+  SendTouchEventACK(blink::WebInputEvent::TouchStart, press1.unique_event_id(),
                     INPUT_EVENT_ACK_STATE_CONSUMED);
 
   ui::TouchEvent press2(
       ui::ET_TOUCH_PRESSED, gfx::Point(20, 20), 1, ui::EventTimeForNow());
   view_->OnTouchEvent(&press2);
-  SendInputEventACK(blink::WebInputEvent::TouchStart,
+  SendTouchEventACK(blink::WebInputEvent::TouchStart, press2.unique_event_id(),
                     INPUT_EVENT_ACK_STATE_CONSUMED);
 
   EXPECT_EQ(2U, view_->dispatcher_->processed_touch_event_count());