Implement compositor thread VSync aligned event queue

ui/events/blink/event_with_callback.h

+// Copyright 2016 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 UI_EVENTS_BLINK_EVENT_WITH_CALLBACK_H_
+#define UI_EVENTS_BLINK_EVENT_WITH_CALLBACK_H_
+
+#include <list>
+
+#include "ui/events/blink/input_handler_proxy.h"
+#include "ui/events/latency_info.h"
+
+namespace ui {
+
+namespace test {
+class InputHandlerProxyEventQueueTest;
+}
+
+class EventWithCallback {
+ public:
+  EventWithCallback(
+      ScopedWebInputEvent event,
+      const LatencyInfo& latency,
+      const InputHandlerProxy::EventDispositionCallback& callback);
+  ~EventWithCallback();
+
+  bool CanCoalesceWith(const EventWithCallback& other) const WARN_UNUSED_RESULT;
+  void CoalesceWith(EventWithCallback* other);
+
+  const blink::WebInputEvent& event() const { return *event_; }
+  const LatencyInfo latencyInfo() const { return latency_; }
+  base::TimeTicks creationTimestamp() const { return creation_timestamp_; }
+  base::TimeTicks lastCoalescedTimestamp() const {
+    return last_coalesced_timestamp_;
+  }
+  size_t coalescedCount() const { return original_events_.size(); }
+
+  void RunCallbacks(InputHandlerProxy::EventDisposition,
+                    const LatencyInfo& latency,
+                    std::unique_ptr<DidOverscrollParams>);
+
+ private:
+  friend class test::InputHandlerProxyEventQueueTest;
+  struct OriginalEventWithCallback {
+    OriginalEventWithCallback(
+        ScopedWebInputEvent event,
+        const InputHandlerProxy::EventDispositionCallback& callback);
+    ~OriginalEventWithCallback();
+    ScopedWebInputEvent event_;
+    InputHandlerProxy::EventDispositionCallback callback_;
+  };
+
+  ScopedWebInputEvent event_;
+  LatencyInfo latency_;
+  std::list<OriginalEventWithCallback> original_events_;
+
+  base::TimeTicks creation_timestamp_;
+  base::TimeTicks last_coalesced_timestamp_;
+
+  // Testing only
+  static std::unique_ptr<base::TimeTicks> testing_timestamp_now_;

[dtapuska, 2016/11/09 21:28:05]

This is kind of clunky. I'd prefer and examples I have seen in unit tests is to
pass the TickClock in.. 

And have the unit test implement a TickClock. There are numerous examples;
https://cs.chromium.org/chromium/src/net/socket/tcp_socket_posix.h?q=TickCloc...

You'll need to probably somehow be able to set the tick clock on your input
handler proxy but that probably is alright.

[chongz, 2016/11/11 21:52:04]

Done.

+};
+
+}  // namespace ui
+
+#endif  // UI_EVENTS_BLINK_EVENT_WITH_CALLBACK_H_