Upload textures through GPU path to non-8-bit color formats won't work in WebGL2

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

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 774 matching lines @@
         TexSubImage2DByGPU,
         TexSubImage3DByGPU
     };
     enum TexImageDimension {
         Tex2D,
         Tex3D
     };
     // Copy from the canvas element directly to the texture via the GPU, without a read-back to system memory.
     void texImageCanvasByGPU(TexImageByGPUType, WebGLTexture*, GLenum target, GLint level,
         GLint internalformat, GLenum type, GLint xoffset, GLint yoffset, GLint zoffset, HTMLCanvasElement*);
-    bool canUseTexImageCanvasByGPU(GLint internalformat, GLenum type);
+    virtual bool canUseTexImageCanvasByGPU(GLint internalformat, GLenum type);
 
     virtual WebGLImageConversion::PixelStoreParams getPackPixelStoreParams();
     virtual WebGLImageConversion::PixelStoreParams getUnpackPixelStoreParams(TexImageDimension);
 
     // Helper function for copyTex{Sub}Image, check whether the internalformat
     // and the color buffer format of the current bound framebuffer combination
     // is valid.
     bool isTexInternalFormatColorBufferCombinationValid(GLenum texInternalFormat, GLenum colorBufferFormat);
 
     // Helper function to verify limits on the length of uniform and attribute locations.
@@ skipping 287 matching lines @@
     static PassOwnPtr<WebGraphicsContext3DProvider> createContextProviderInternal(HTMLCanvasElement*, ScriptState*, WebGLContextAttributes, unsigned);
 };
 
 DEFINE_TYPE_CASTS(WebGLRenderingContextBase, CanvasRenderingContext, context, context->is3d(), context.is3d());
 
 } // namespace blink
 
 WTF_ALLOW_MOVE_INIT_AND_COMPARE_WITH_MEM_FUNCTIONS(blink::WebGLRenderingContextBase::TextureUnitState);
 
 #endif // WebGLRenderingContextBase_h