Enforce queries' new availability semantics.

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

Index: third_party/WebKit/Source/modules/webgl/WebGLQuery.h
diff --git a/third_party/WebKit/Source/modules/webgl/WebGLQuery.h b/third_party/WebKit/Source/modules/webgl/WebGLQuery.h
index c4ef7d9f48e1c102f44e27cfca6bee9182446b64..867cc49dcb3649b52f59233d9eb39efda3e925e7 100644
--- a/third_party/WebKit/Source/modules/webgl/WebGLQuery.h
+++ b/third_party/WebKit/Source/modules/webgl/WebGLQuery.h
@@ -11,7 +11,7 @@ namespace blink {
 
 class WebGL2RenderingContextBase;
 
-class WebGLQuery : public WebGLSharedPlatform3DObject {
+class WebGLQuery : public WebGLSharedPlatform3DObject, public WebThread::TaskObserver {
     DEFINE_WRAPPERTYPEINFO();
 public:
     ~WebGLQuery() override;
@@ -19,8 +19,15 @@ public:
     static WebGLQuery* create(WebGL2RenderingContextBase*);
 
     void setTarget(GLenum);
+    bool hasTarget() const { return m_target != 0; }
     GLenum getTarget() const { return m_target; }
 
+    void resetCachedResult();
+    void updateCachedResult(WebGraphicsContext3D*);
+
+    bool isQueryResultAvailable();
+    GLuint getQueryResult();
+
 protected:
     explicit WebGLQuery(WebGL2RenderingContextBase*);
 
@@ -29,7 +36,19 @@ protected:
 private:
     bool isQuery() const override { return true; }
 
+    void registerTaskObserver();
+    void unregisterTaskObserver();
+
+    // TaskObserver implementation.
+    void didProcessTask() override;
+    void willProcessTask() override { }
+
     GLenum m_target;
+
+    bool m_taskObserverRegistered;
+    bool m_canUpdateAvailability;
+    bool m_queryResultAvailable;
+    GLuint m_queryResult;
 };
 
 } // namespace blink