webgl: Replace query task observer with a posted task

third_party/WebKit/Source/modules/webgl/WebGLTimerQueryEXT.h

 // 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 WebGLTimerQueryEXT_h
 #define WebGLTimerQueryEXT_h
 
 #include "modules/webgl/WebGLContextObject.h"
-
-#include "public/platform/WebThread.h"
+#include "platform/scheduler/CancellableTaskFactory.h"
 
 namespace gpu {
 namespace gles2 {
 class GLES2Interface;
 }
 }
 
 namespace blink {
 
-class WebGLTimerQueryEXT : public WebGLContextObject, public WebThread::TaskObserver {
+class WebTaskRunner;
+
+class WebGLTimerQueryEXT : public WebGLContextObject {
     DEFINE_WRAPPERTYPEINFO();
 
 public:
     static WebGLTimerQueryEXT* create(WebGLRenderingContextBase*);
     ~WebGLTimerQueryEXT() override;
 
     void setTarget(GLenum target) { m_target = target; }
 
     GLuint object() const { return m_queryId; }
     bool hasTarget() const { return m_target != 0; }
     GLenum target() const { return m_target; }
 
     void resetCachedResult();
     void updateCachedResult(gpu::gles2::GLES2Interface*);
 
     bool isQueryResultAvailable();
     GLuint64 getQueryResult();
 
 protected:
     WebGLTimerQueryEXT(WebGLRenderingContextBase*);
 
 private:
     bool hasObject() const override { return m_queryId != 0; }
     void deleteObjectImpl(gpu::gles2::GLES2Interface*) override;
 
-    void registerTaskObserver();
-    void unregisterTaskObserver();
-
-    // TaskObserver implementation.
-    void didProcessTask() override;
-    void willProcessTask() override { }
+    void scheduleAllowAvailabilityUpdate();
+    void allowAvailabilityUpdate();
 
     GLenum m_target;
     GLuint m_queryId;
 
-    bool m_taskObserverRegistered;
     bool m_canUpdateAvailability;
     bool m_queryResultAvailable;
     GLuint64 m_queryResult;
+
+    std::unique_ptr<WebTaskRunner> m_taskRunner;
+    std::unique_ptr<CancellableTaskFactory> m_cancellableTaskFactory;
 };
 
 } // namespace blink
 
 #endif // WebGLTimerQueryEXT_h