command_buffer: Implement CHROMIUM_framebuffer_mixed_samples extension

mojo/gpu/mojo_gles2_impl_autogen.cc

Index: mojo/gpu/mojo_gles2_impl_autogen.cc
diff --git a/mojo/gpu/mojo_gles2_impl_autogen.cc b/mojo/gpu/mojo_gles2_impl_autogen.cc
index 5818a65477e51bd0afc871357fd56cb6f3d3206a..7821ba8c7fd41057f7a9af1442d9f0b51baf4d6e 100644
--- a/mojo/gpu/mojo_gles2_impl_autogen.cc
+++ b/mojo/gpu/mojo_gles2_impl_autogen.cc
@@ -1908,6 +1908,10 @@ void MojoGLES2Impl::ProgramPathFragmentInputGenCHROMIUM(GLuint program,
   glProgramPathFragmentInputGenCHROMIUM(program, location, genMode, components,
                                         coeffs);
 }
+void MojoGLES2Impl::CoverageModulationCHROMIUM(GLenum components) {
+  MojoGLES2MakeCurrent(context_);
+  glCoverageModulationCHROMIUM(components);
+}
 GLenum MojoGLES2Impl::GetGraphicsResetStatusKHR() {
   MojoGLES2MakeCurrent(context_);
   return glGetGraphicsResetStatusKHR();