webgl: Replace query task observer with a posted task

third_party/WebKit/Source/modules/webgl/WebGLQuery.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 WebGLQuery_h
 #define WebGLQuery_h
 
 #include "modules/webgl/WebGLSharedPlatform3DObject.h"
+#include "platform/scheduler/CancellableTaskFactory.h"
 
 namespace gpu {
 namespace gles2 {
 class GLES2Interface;
 }
 }
 
 namespace blink {
 
 class WebGL2RenderingContextBase;
+class WebTaskRunner;
 
-class WebGLQuery : public WebGLSharedPlatform3DObject, public WebThread::TaskObserver {
+class WebGLQuery : public WebGLSharedPlatform3DObject {
     DEFINE_WRAPPERTYPEINFO();
 public:
     ~WebGLQuery() override;
 
     static WebGLQuery* create(WebGL2RenderingContextBase*);
 
     void setTarget(GLenum);
     bool hasTarget() const { return m_target != 0; }
     GLenum getTarget() const { return m_target; }
 
     void resetCachedResult();
     void updateCachedResult(gpu::gles2::GLES2Interface*);
 
     bool isQueryResultAvailable();
     GLuint getQueryResult();
 
 protected:
     explicit WebGLQuery(WebGL2RenderingContextBase*);
 
     void deleteObjectImpl(gpu::gles2::GLES2Interface*) override;
 
 private:
     bool isQuery() const override { return true; }
 
-    void registerTaskObserver();
-    void unregisterTaskObserver();
-
-    // TaskObserver implementation.
-    void didProcessTask() override;
-    void willProcessTask() override { }
+    void scheduleAllowAvailabilityUpdate();
+    void allowAvailabilityUpdate();
 
     GLenum m_target;
 
-    bool m_taskObserverRegistered;
     bool m_canUpdateAvailability;
     bool m_queryResultAvailable;
     GLuint m_queryResult;
+
+    std::unique_ptr<WebTaskRunner> m_taskRunner;
+    std::unique_ptr<CancellableTaskFactory> m_cancellableTaskFactory;
 };
 
 } // namespace blink
 
 #endif // WebGLQuery_h