Add GL_CHROMIUM_screen_space_antialiasing to support alternative AA

gpu/blink/webgraphicscontext3d_impl.cc

 // Copyright (c) 2012 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 "gpu/blink/webgraphicscontext3d_impl.h"
 
 #include "base/atomicops.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "gpu/GLES2/gl2extchromium.h"
@@ skipping 240 matching lines @@
       dstX0, dstY0, dstX1, dstY1,
       mask, filter);
 }
 
 DELEGATE_TO_GL_5(renderbufferStorageMultisampleCHROMIUM,
                  RenderbufferStorageMultisampleCHROMIUM, WGC3Denum, WGC3Dsizei,
                  WGC3Denum, WGC3Dsizei, WGC3Dsizei)
 
 DELEGATE_TO_GL_1(activeTexture, ActiveTexture, WGC3Denum)
 
+DELEGATE_TO_GL(applyScreenSpaceAntialiasingCHROMIUM,
+               ApplyScreenSpaceAntialiasingCHROMIUM);
+
 DELEGATE_TO_GL_2(attachShader, AttachShader, WebGLId, WebGLId)
 
 DELEGATE_TO_GL_3(bindAttribLocation, BindAttribLocation, WebGLId,
                  WGC3Duint, const WGC3Dchar*)
 
 DELEGATE_TO_GL_2(bindBuffer, BindBuffer, WGC3Denum, WebGLId)
 
 DELEGATE_TO_GL_2(bindFramebuffer, BindFramebuffer, WGC3Denum, WebGLId)
 
 DELEGATE_TO_GL_2(bindRenderbuffer, BindRenderbuffer, WGC3Denum, WebGLId)
@@ skipping 977 matching lines @@
   output_attribs->stencil_size = attributes.stencil ? 8 : 0;
   output_attribs->samples = attributes.antialias ? 4 : 0;
   output_attribs->sample_buffers = attributes.antialias ? 1 : 0;
   output_attribs->fail_if_major_perf_caveat =
       attributes.failIfMajorPerformanceCaveat;
   output_attribs->bind_generates_resource = false;
   output_attribs->webgl_version = attributes.webGLVersion;
 }
 
 }  // namespace gpu_blink