gpu: Use workarounds to selectively enable CMAA

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 <stddef.h>
 
 #include <set>
 #include <vector>
@@ skipping 874 matching lines @@
        extensions.Contains("GL_EXT_multisample_compatibility")) {
     AddExtensionString("GL_EXT_multisample_compatibility");
     feature_flags_.ext_multisample_compatibility = true;
     validators_.capability.AddValue(GL_MULTISAMPLE_EXT);
     validators_.capability.AddValue(GL_SAMPLE_ALPHA_TO_ONE_EXT);
   }
 
   if (extensions.Contains("GL_INTEL_framebuffer_CMAA")) {
     feature_flags_.chromium_screen_space_antialiasing = true;
     AddExtensionString("GL_CHROMIUM_screen_space_antialiasing");
-  } else if (enable_cmaa_shaders_switch_ &&
+  } else if ((enable_cmaa_shaders_switch_ ||

[Zhenyao Mo, 2016/06/29 16:59:16]

You should just get rid of this enable_cmaa_shaders_switch_ and its related code
now that we have the driver bug workaround installed.

[robert.bradford, 2016/06/29 17:39:46]

Done.

+              !workarounds_.disable_framebuffer_cmaa) &&
              (gl_version_info_->IsAtLeastGLES(3, 1) ||
               (gl_version_info_->IsAtLeastGL(3, 0) &&
                extensions.Contains("GL_ARB_shading_language_420pack") &&
                extensions.Contains("GL_ARB_texture_gather") &&
                extensions.Contains("GL_ARB_explicit_uniform_location") &&
                extensions.Contains("GL_ARB_explicit_attrib_location") &&
                extensions.Contains("GL_ARB_shader_image_load_store")))) {
     feature_flags_.chromium_screen_space_antialiasing = true;
     feature_flags_.use_chromium_screen_space_antialiasing_via_shaders = true;
     AddExtensionString("GL_CHROMIUM_screen_space_antialiasing");
@@ skipping 509 matching lines @@
   if (pos == std::string::npos) {
     extensions_ += (extensions_.empty() ? "" : " ") + str;
   }
 }
 
 FeatureInfo::~FeatureInfo() {
 }
 
 }  // namespace gles2
 }  // namespace gpu