Fix crash from state management cleanup

third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.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 WebGL2RenderingContextBase_h
 #define WebGL2RenderingContextBase_h
 
 #include "modules/webgl/WebGLExtension.h"
 #include "modules/webgl/WebGLRenderingContextBase.h"
 #include <memory>
@@ skipping 710 matching lines @@
   DECLARE_VIRTUAL_TRACE_WRAPPERS();
 
  protected:
   friend class V8WebGL2RenderingContext;
 
   WebGL2RenderingContextBase(
       HTMLCanvasElement*,
       std::unique_ptr<WebGraphicsContext3DProvider>,
       const CanvasContextCreationAttributes& requestedAttributes);
 
+  // DrawingBuffer::Client implementation.
+  void DrawingBufferClientRestorePixelUnpackBufferBinding() override;
+
   // Helper function to validate target and the attachment combination for
   // getFramebufferAttachmentParameters.  Generate GL error and return false if
   // parameters are illegal.
   bool validateGetFramebufferAttachmentParameterFunc(const char* functionName,
                                                      GLenum target,
                                                      GLenum attachment);
 
   bool validateClearBuffer(const char* functionName,
                            GLenum buffer,
                            GLsizei length);
@@ skipping 126 matching lines @@
                   context,
                   context->is3d() &&
                       WebGLRenderingContextBase::getWebGLVersion(context) >= 2,
                   context.is3d() &&
                       WebGLRenderingContextBase::getWebGLVersion(&context) >=
                           2);
 
 }  // namespace blink
 
 #endif