WebGL 2: remove incorrect enum value for buffer in clearBuffer

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

 // 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.
 
 #include "modules/webgl/WebGL2RenderingContextBase.h"
 
 #include "bindings/modules/v8/WebGLAny.h"
 #include "core/html/HTMLCanvasElement.h"
 #include "core/html/HTMLImageElement.h"
 #include "core/html/HTMLVideoElement.h"
@@ skipping 1587 matching lines @@
             }
         }
         m_framebufferBinding->drawBuffers(buffers);
     }
 }
 
 bool WebGL2RenderingContextBase::validateClearBuffer(const char* functionName, GLenum buffer, GLsizei size)
 {
     switch (buffer) {
     case GL_COLOR:
-    case GL_FRONT:
-    case GL_BACK:
-    case GL_FRONT_AND_BACK:

[qiankun, 2016/01/13 06:11:35]

INVALID_EUNUM should be genereated for the invalid buffer. See Page 190 in ES
3.0.4 spec: https://www.khronos.org/registry/gles/specs/3.0/es_spec_3.0.4.pdf.

I think you can add tests to validate this.

[yunchao, 2016/01/13 07:52:18]

It is not possible to expose the error by adding webgl conformance test for this
case, because the command buffer has validation code to verify the argument
'buffer'. Command buffer service side can report INVALID_ENUM against
FRONT/BACK/FRONT_AND_BACK.

However, validateClearBuffer() is necessary to verify the 'size' argument. We
can not remove this function. 

         if (size < 4) {
             synthesizeGLError(GL_INVALID_VALUE, functionName, "invalid array size");
             return false;
         }
         break;
     case GL_DEPTH:
     case GL_STENCIL:
         if (size < 1) {
             synthesizeGLError(GL_INVALID_VALUE, functionName, "invalid array size");
             return false;
@@ skipping 1928 matching lines @@
 
     WebGLSampler* sampler = m_samplerUnits[unit];
 
     if (sampler)
         return sampler->getSamplerState();
 
     return WebGLRenderingContextBase::getTextureUnitSamplerState(target, unit);
 }
 
 } // namespace blink