Add GL_CHROMIUM_screen_space_antialiasing to support alternative AA

gpu/command_buffer/service/feature_info.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/command_buffer/service/feature_info.h"
 
 #include <set>
 #include <vector>
 
 #include "base/command_line.h"
@@ skipping 112 matching lines @@
 }  // anonymous namespace.
 
 FeatureInfo::FeatureFlags::FeatureFlags()
     : chromium_color_buffer_float_rgba(false),
       chromium_color_buffer_float_rgb(false),
       chromium_framebuffer_multisample(false),
       chromium_sync_query(false),
       use_core_framebuffer_multisample(false),
       multisampled_render_to_texture(false),
       use_img_for_multisampled_render_to_texture(false),
+      chromium_screen_space_antialiasing(false),
       oes_standard_derivatives(false),
       oes_egl_image_external(false),
       oes_depth24(false),
       oes_compressed_etc1_rgb8_texture(false),
       packed_depth24_stencil8(false),
       npot_ok(false),
       enable_texture_float_linear(false),
       enable_texture_half_float_linear(false),
       angle_translated_shader_source(false),
       angle_pack_reverse_row_order(false),
@@ skipping 583 matching lines @@
     if (feature_flags_.multisampled_render_to_texture) {
       validators_.render_buffer_parameter.AddValue(
           GL_RENDERBUFFER_SAMPLES_EXT);
       validators_.g_l_state.AddValue(GL_MAX_SAMPLES_EXT);
       validators_.frame_buffer_parameter.AddValue(
           GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_SAMPLES_EXT);
       AddExtensionString("GL_EXT_multisampled_render_to_texture");
     }
   }
 
+  if (extensions.Contains("GL_INTEL_framebuffer_CMAA")) {
+    feature_flags_.chromium_screen_space_antialiasing = true;
+    AddExtensionString("GL_CHROMIUM_screen_space_antialiasing");
+  }
+
   if (extensions.Contains("GL_OES_depth24") || gfx::HasDesktopGLFeatures() ||
       gl_version_info_->is_es3) {
     AddExtensionString("GL_OES_depth24");
     feature_flags_.oes_depth24 = true;
     validators_.render_buffer_format.AddValue(GL_DEPTH_COMPONENT24);
   }
 
   if (gl_version_info_->is_es3 ||
       extensions.Contains("GL_OES_standard_derivatives") ||
       gfx::HasDesktopGLFeatures()) {
@@ skipping 450 matching lines @@
   if (pos == std::string::npos) {
     extensions_ += (extensions_.empty() ? "" : " ") + str;
   }
 }
 
 FeatureInfo::~FeatureInfo() {
 }
 
 }  // namespace gles2
 }  // namespace gpu