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

gpu/command_buffer/service/gles2_cmd_decoder.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index 7ecd8d5f47bf07b2f1410eb945e5d1295423c7b6..2add27318f7fb11e594c1c0dd6c05ab53d9dd346 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -2742,6 +2742,13 @@ bool GLES2DecoderImpl::Initialize(const scoped_refptr<gfx::GLSurface>& surface,
     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());