Only make timer queries' results available when control returns to browser.

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"
+
 namespace blink {
 
-class WebGLTimerQueryEXT : public WebGLContextObject {
+class WebGLTimerQueryEXT : public WebGLContextObject, public WebThread::TaskObserver {
     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(WebGraphicsContext3D*);
+
+    bool isQueryResultAvailable();
+    GLuint64 getQueryResult();
+
 protected:
     WebGLTimerQueryEXT(WebGLRenderingContextBase*);
 
 private:
     bool hasObject() const override { return m_queryId != 0; }
     void deleteObjectImpl(WebGraphicsContext3D*) override;
 
+    void registerTaskObserver();
+    void unregisterTaskObserver();
+
+    // TaskObserver implementation.
+    void didProcessTask() override;
+    void willProcessTask() override { }
+
     GLenum m_target;
     GLuint m_queryId;
+
+    bool m_taskObserverRegistered;
+    bool m_canUpdateAvailability;
+    bool m_queryResultAvailable;
+    GLuint64 m_queryResult;
 };
 
 } // namespace blink
 
 #endif // WebGLTimerQueryEXT_h