Enable TexStorage on Desktop GL lower than 4.2

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 1016 matching lines @@
   // claim to handle GL_BGRA8.
   bool support_texture_storage_on_es3 =
       (gl_version_info_->is_es3 &&
        enable_immutable_texture_format_bgra_on_es3) ||
       (gl_version_info_->is_es3 &&
        !enable_texture_format_bgra8888);
   if (!workarounds_.disable_texture_storage &&
       (extensions.Contains("GL_EXT_texture_storage") ||
        extensions.Contains("GL_ARB_texture_storage") ||
        support_texture_storage_on_es3 ||
-       gl_version_info_->is_desktop_core_profile)) {
+       gl_version_info_->IsAtLeastGL(4, 2))) {

[piman, 2016/04/11 22:59:31]

I'm a bit confused... Is the goal to expose GL_EXT_texture_storage on the client
even when GL < 4.2? If so, it sounds like you would want to remove this check.
If not, I'm not sure how the client is supposed to know that calling TexStorage*
is allowed.

[Zhenyao Mo, 2016/04/11 23:17:19]

My bad.  I got my two different options mixed.

Option 1: implement the workaround.
Option 2: after I check various Mac devices, it seems ARB_texture_storage is
widely supported, so the workaround may not be necessary at all. We just need to
fix the gl bindings to make it work.

Let's go down option 2 for now, unless situations arise where a Mac driver
doesn't have the extension.

     feature_flags_.ext_texture_storage = true;
     AddExtensionString("GL_EXT_texture_storage");
     validators_.texture_parameter.AddValue(GL_TEXTURE_IMMUTABLE_FORMAT_EXT);
     if (enable_texture_format_bgra8888)
         validators_.texture_internal_format_storage.AddValue(GL_BGRA8_EXT);
     if (enable_texture_float) {
         validators_.texture_internal_format_storage.AddValue(GL_RGBA32F_EXT);
         validators_.texture_internal_format_storage.AddValue(GL_RGB32F_EXT);
         validators_.texture_internal_format_storage.AddValue(GL_ALPHA32F_EXT);
         validators_.texture_internal_format_storage.AddValue(
@@ skipping 376 matching lines @@
   if (pos == std::string::npos) {
     extensions_ += (extensions_.empty() ? "" : " ") + str;
   }
 }
 
 FeatureInfo::~FeatureInfo() {
 }
 
 }  // namespace gles2
 }  // namespace gpu