command_buffer: Implement CHROMIUM_framebuffer_mixed_samples extension

mojo/public/c/gles2/gles2_call_visitor_chromium_extension_autogen.h

 // Copyright 2014 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.
 
 // This file is auto-generated from
 // gpu/command_buffer/build_gles2_cmd_buffer.py
 // It's formatted by clang-format using chromium coding style:
 //    clang-format -i -style=chromium filename
 // DO NOT EDIT!
 
@@ skipping 547 matching lines @@
               (GLuint program, GLint location, const char* name),
               (program, location, name))
 VISIT_GL_CALL(ProgramPathFragmentInputGenCHROMIUM,
               void,
               (GLuint program,
                GLint location,
                GLenum genMode,
                GLint components,
                const GLfloat* coeffs),
               (program, location, genMode, components, coeffs))
+VISIT_GL_CALL(CoverageModulationCHROMIUM,
+              void,
+              (GLenum components),
+              (components))
 VISIT_GL_CALL(GetGraphicsResetStatusKHR, GLenum, (), ())
 VISIT_GL_CALL(BlendBarrierKHR, void, (), ())
 VISIT_GL_CALL(ApplyScreenSpaceAntialiasingCHROMIUM, void, (), ())
 VISIT_GL_CALL(
     BindFragDataLocationIndexedEXT,
     void,
     (GLuint program, GLuint colorNumber, GLuint index, const char* name),
     (program, colorNumber, index, name))
 VISIT_GL_CALL(BindFragDataLocationEXT,
               void,
               (GLuint program, GLuint colorNumber, const char* name),
               (program, colorNumber, name))
 VISIT_GL_CALL(GetFragDataIndexEXT,
               GLint,
               (GLuint program, const char* name),
               (program, name))