Fix state management of transform feedback buffers.

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

Index: third_party/WebKit/Source/modules/webgl/WebGLTransformFeedback.h
diff --git a/third_party/WebKit/Source/modules/webgl/WebGLTransformFeedback.h b/third_party/WebKit/Source/modules/webgl/WebGLTransformFeedback.h
index be3551d95fe97cba9b8509811d2351403ef6cc34..f0a748ce057bdcdfb14a19d2f62219f64898eb7a 100644
--- a/third_party/WebKit/Source/modules/webgl/WebGLTransformFeedback.h
+++ b/third_party/WebKit/Source/modules/webgl/WebGLTransformFeedback.h
@@ -12,14 +12,22 @@
 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);
@@ -29,18 +37,37 @@ class WebGLTransformFeedback : public WebGLSharedPlatform3DObject {
   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;
 };