Fix state management of transform feedback buffers.

third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.h

Index: third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.h
diff --git a/third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.h b/third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.h
index 1578fbd080ef83f8d72035a71029db3d45ce20d5..37f55ab087b9dac6509da47c67d2e1c9182608e5 100644
--- a/third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.h
+++ b/third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.h
@@ -940,6 +940,9 @@ class WebGL2RenderingContextBase : public WebGLRenderingContextBase {
                   DOMArrayBufferView* pixels) override;
   void restoreCurrentFramebuffer() override;
 
+  /* Helpers */
+  GLint getMaxTransformFeedbackSeparateAttribs() const;
+
   DECLARE_VIRTUAL_TRACE();
   DECLARE_VIRTUAL_TRACE_WRAPPERS();
 
@@ -1076,6 +1079,9 @@ class WebGL2RenderingContextBase : public WebGLRenderingContextBase {
 
   TraceWrapperMember<WebGLFramebuffer> m_readFramebufferBinding;
   TraceWrapperMember<WebGLTransformFeedback> m_transformFeedbackBinding;
+  // This instance isn't exposed to JavaScript, which is why it's a
+  // Member rather than TraceWrapperMember.
+  Member<WebGLTransformFeedback> m_defaultTransformFeedback;
 
   std::set<GLenum> m_supportedInternalFormatsStorage;
   std::set<GLenum> m_compressedTextureFormatsETC2EAC;
@@ -1084,11 +1090,8 @@ class WebGL2RenderingContextBase : public WebGLRenderingContextBase {
   TraceWrapperMember<WebGLBuffer> m_boundCopyWriteBuffer;
   TraceWrapperMember<WebGLBuffer> m_boundPixelPackBuffer;
   TraceWrapperMember<WebGLBuffer> m_boundPixelUnpackBuffer;
-  TraceWrapperMember<WebGLBuffer> m_boundTransformFeedbackBuffer;
   TraceWrapperMember<WebGLBuffer> m_boundUniformBuffer;
 
-  HeapVector<TraceWrapperMember<WebGLBuffer>>
-      m_boundIndexedTransformFeedbackBuffers;
   HeapVector<TraceWrapperMember<WebGLBuffer>> m_boundIndexedUniformBuffers;
   GLint m_maxTransformFeedbackSeparateAttribs;
   size_t m_maxBoundUniformBufferIndex;