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 2724 matching lines @@
       LOG(ERROR) << "Underlying driver does not support ES3.";
       Destroy(true);
       return false;
     }
     feature_info_->EnableES3Validators();
     set_unsafe_es3_apis_enabled(true);
 
     frag_depth_explicitly_enabled_ = true;
     draw_buffers_explicitly_enabled_ = true;
     // TODO(zmo): Look into shader_texture_lod_explicitly_enabled_ situation.
+
+    // TEXTURE_CUBE_MAP_SEAMLESS is available on Desktop GL 3.2 or above.
+    // ES3 requires it to be always supported.
+    // We don't support ES3 on Desktop GL lower than 3.2.
+    if (!feature_info_->gl_version_info().BehavesLikeGLES()) {
+      glEnable(GL_TEXTURE_CUBE_MAP_SEAMLESS);
+    }

[piman, 2016/03/24 22:24:06]

Let's just turn it on always, even for es2 contexts, it's more consistent.
As is, if we use virtual contexts, the state will leak to es2 contexts if you
ever create an es3 one. For repeatability, let's just be consistent. The
alternative is to turn it on or off on a context switch, but that sounds like
more work.

   }
 
   state_.attrib_values.resize(group_->max_vertex_attribs());
   vertex_array_manager_.reset(new VertexArrayManager());
 
   GLuint default_vertex_attrib_service_id = 0;
   if (features().native_vertex_array_object) {
     glGenVertexArraysOES(1, &default_vertex_attrib_service_id);
     glBindVertexArrayOES(default_vertex_attrib_service_id);
   }
@@ skipping 13578 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