Fix state management of transform feedback buffers.

third_party/WebKit/Source/modules/webgl/WebGLTransformFeedback.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 WebGLTransformFeedback_h
 #define WebGLTransformFeedback_h
 
 #include "modules/webgl/WebGLProgram.h"
 #include "modules/webgl/WebGLSharedPlatform3DObject.h"
 #include "wtf/PassRefPtr.h"
 
 namespace blink {
 
 class WebGL2RenderingContextBase;
+class WebGLBuffer;
 
 class WebGLTransformFeedback : public WebGLSharedPlatform3DObject {
   DEFINE_WRAPPERTYPEINFO();
 
  public:
+  enum TFType {
+    TFTypeDefault,
+    TFTypeUser,
+  };
+
   ~WebGLTransformFeedback() override;
 
-  static WebGLTransformFeedback* create(WebGL2RenderingContextBase*);
+  static WebGLTransformFeedback* create(WebGL2RenderingContextBase*, TFType);
+
+  bool isDefaultObject() const { return m_type == TFTypeDefault; }
 
   GLenum getTarget() const { return m_target; }
   void setTarget(GLenum);
 
   bool hasEverBeenBound() const { return object() && m_target; }
 
   WebGLProgram* getProgram() const { return m_program; }
   void setProgram(WebGLProgram*);
 
-  DECLARE_TRACE();
+  // This is the generic bind point for the transform feedback buffer.
+  void setBoundTransformFeedbackBuffer(WebGLBuffer*);
+  WebGLBuffer* getBoundTransformFeedbackBuffer() const;
+
+  // These are the indexed bind points for transform feedback buffers.
+  // Returns false if index is out of range and the caller should
+  // synthesize a GL error.
+  bool setBoundIndexedTransformFeedbackBuffer(GLuint index, WebGLBuffer*);
+  bool getBoundIndexedTransformFeedbackBuffer(GLuint index,
+                                              WebGLBuffer** outBuffer) const;
+
+  bool isBufferBoundToTransformFeedback(WebGLBuffer*);
+
+  DECLARE_VIRTUAL_TRACE();
+  DECLARE_VIRTUAL_TRACE_WRAPPERS();
 
  protected:
-  explicit WebGLTransformFeedback(WebGL2RenderingContextBase*);
+  explicit WebGLTransformFeedback(WebGL2RenderingContextBase*, TFType);
 
   void deleteObjectImpl(gpu::gles2::GLES2Interface*) override;
 
  private:
   bool isTransformFeedback() const override { return true; }
 
+  TFType m_type;
   GLenum m_target;
 
+  TraceWrapperMember<WebGLBuffer> m_boundTransformFeedbackBuffer;
+  HeapVector<TraceWrapperMember<WebGLBuffer>>
+      m_boundIndexedTransformFeedbackBuffers;
+
   Member<WebGLProgram> m_program;
 };
 
 }  // namespace blink
 
 #endif  // WebGLTransformFeedback_h