Emulate TEXTURE_IMMUTABLE_LEVELS on GL lower than 4.2

gpu/command_buffer/service/texture_manager.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/texture_manager.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 1301 matching lines @@
         if (!ClearLevel(decoder, info.target, jj)) {
           return false;
         }
       }
     }
   }
   UpdateSafeToRenderFrom(true);
   return true;
 }
 
+GLint Texture::GetImmutableLevels() const {
+  if (!immutable_)
+    return 0;
+  GLint levels = 0;
+  if (immutable_) {
+    DCHECK(face_infos_.size() > 0);
+    for (size_t ii = 0; ii < face_infos_[0].level_infos.size(); ++ii) {
+      const Texture::LevelInfo& info = face_infos_[0].level_infos[ii];
+      if (info.target != 0)
+        levels++;
+    }
+  }
+  return levels;
+}
+
 gfx::Rect Texture::GetLevelClearedRect(GLenum target, GLint level) const {
   size_t face_index = GLES2Util::GLTargetToFaceIndex(target);
   if (face_index >= face_infos_.size() ||
       level >= static_cast<GLint>(face_infos_[face_index].level_infos.size())) {
     return gfx::Rect();
   }
 
   const Texture::LevelInfo& info = face_infos_[face_index].level_infos[level];
 
   return info.cleared_rect;
@@ skipping 1802 matching lines @@
 uint32_t TextureManager::GetServiceIdGeneration() const {
   return current_service_id_generation_;
 }
 
 void TextureManager::IncrementServiceIdGeneration() {
   current_service_id_generation_++;
 }
 
 }  // namespace gles2
 }  // namespace gpu