Turn on seamless cubemap by default on Desktop GL for ES3.

gpu/command_buffer/service/gles2_cmd_decoder.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/gles2_cmd_decoder.h"
 
 #include <limits.h>
 #include <stddef.h>
 #include <stdint.h>
 #include <stdio.h>
@@ skipping 3000 matching lines @@
   // variable in fragment shaders.
   if (!feature_info_->gl_version_info().BehavesLikeGLES()) {
     glEnable(GL_VERTEX_PROGRAM_POINT_SIZE);
     glEnable(GL_POINT_SPRITE);
   } else if (feature_info_->gl_version_info().is_desktop_core_profile) {
     // The desktop core profile changed how program point size mode is
     // enabled.
     glEnable(GL_PROGRAM_POINT_SIZE);
   }
 
+  // ES3 requires seamless cubemap. ES2 does not.
+  // However, when ES2 is implemented on top of DX11, seamless cubemap is
+  // always enabled and there is no way to disable it.
+  // Therefore, it seems OK to also always enable it on top of Desktop GL for
+  // both ES2 and ES3 contexts.
+  if (feature_info_->gl_version_info().IsAtLeastGL(3, 2)) {
+    glEnable(GL_TEXTURE_CUBE_MAP_SEAMLESS);
+  }
+
   has_robustness_extension_ =
       context->HasExtension("GL_ARB_robustness") ||
       context->HasExtension("GL_KHR_robustness") ||
       context->HasExtension("GL_EXT_robustness");
 
   if (!InitializeShaderTranslator()) {
     return false;
   }
 
   GLint viewport_params[4] = { 0 };
@@ skipping 13302 matching lines @@
 }
 
 // Include the auto-generated part of this file. We split this because it means
 // we can easily edit the non-auto generated parts right here in this file
 // instead of having to edit some template or the code generator.
 #include "base/macros.h"
 #include "gpu/command_buffer/service/gles2_cmd_decoder_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu