Coalesce async touch move events until the ack back from render

content/common/input/input_event_ack.h

Index: content/common/input/input_event_ack.h
diff --git a/content/common/input/input_event_ack.h b/content/common/input/input_event_ack.h
new file mode 100644
index 0000000000000000000000000000000000000000..1155d2c74d92d280fc5159c6496a43764f74f96e
--- /dev/null
+++ b/content/common/input/input_event_ack.h
@@ -0,0 +1,42 @@
+// Copyright 2015 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.
+
+#ifndef CONTENT_COMMON_INPUT_INPUT_EVENT_ACK_H_
+#define CONTENT_COMMON_INPUT_INPUT_EVENT_ACK_H_
+
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+#include "content/common/content_export.h"
+#include "content/common/input/did_overscroll_params.h"
+#include "content/common/input/input_event_ack_state.h"
+#include "third_party/WebKit/public/web/WebInputEvent.h"
+#include "ui/events/latency_info.h"
+
+namespace content {
+
+// InputEventAck.
+struct CONTENT_EXPORT InputEventAck {
+  InputEventAck(blink::WebInputEvent::Type type,
+                InputEventAckState state,
+                const ui::LatencyInfo& latency,
+                scoped_ptr<content::DidOverscrollParams> overscroll,
+                uint32 unique_touch_event_id);
+  InputEventAck(blink::WebInputEvent::Type type,
+                InputEventAckState state,
+                const ui::LatencyInfo& latency,
+                uint32 unique_touch_event_id);
+  InputEventAck(blink::WebInputEvent::Type type, InputEventAckState state);
+  InputEventAck();
+  ~InputEventAck();
+
+  blink::WebInputEvent::Type type;
+  InputEventAckState state;
+  ui::LatencyInfo latency;
+  scoped_ptr<content::DidOverscrollParams> overscroll;
+  uint32 unique_touch_event_id;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_COMMON_INPUT_INPUT_EVENT_ACK_H_