Ozone: Avoid blocking in Swapbuffer Call.

ui/ozone/platform/dri/page_flip_event_handler.h

+// Copyright 2014 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_OZONE_PLATFORM_PAGE_FLIP_EVENT_HANDLER_H_
+#define UI_OZONE_PLATFORM_PAGE_FLIP_EVENT_HANDLER_H_
+
+#include "base/message_loop/message_loop.h"
+#include "base/synchronization/waitable_event.h"
+#include "base/threading/thread.h"
+#include "ui/ozone/public/surface_ozone_egl.h"
+
+namespace ui {
+
+class HardwareDisplayController;
+
+// Helper class to processes outstanding DRM events of a given HardwareDisplay
+// Controller in a worker thread.
+class PageFlipEventHandler : public base::Thread {
+ public:
+  PageFlipEventHandler();
+
+  ~PageFlipEventHandler() override;
+
+  // Checks if any submitted page flip events for Controller have been processed
+  // and callback is called once this data is available. The function doesn't
+  // block. Query to check if the page flip events have been processed
+  // will be done in a worker thread to make sure we dont block the current
+  // thread but the callback will be posted on the same sequenced thread.
+  void GetPageFlipCompleted(
+      HardwareDisplayController* controller,
+      const ui::SurfaceOzoneEGL::PageFlipCompletionCallback& callback);
+
+ protected:
+  void CleanUp() override;
+
+ private:
+  static void RunFlipEventCallBack(
+      const ui::SurfaceOzoneEGL::PageFlipCompletionCallback& callback);
+
+  static void CheckPageFlipEvent(
+      PageFlipEventHandler* data,
+      HardwareDisplayController* controller,
+      const ui::SurfaceOzoneEGL::PageFlipCompletionCallback& callback);
+
+ private:
+  // Our original calling message loop for the child thread.
+  scoped_refptr<base::MessageLoopProxy> child_message_loop_proxy_;
+  DISALLOW_COPY_AND_ASSIGN(PageFlipEventHandler);
+};
+
+}  // namespace ui
+
+#endif  // UI_OZONE_PLATFORM_PAGE_FLIP_EVENT_HANDLER_H_