gpu: Clarify sized texture format is available only if ES3 context or immutable texture is supported

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 213 matching lines @@
         {GL_RGBA16I, GL_RGBA_INTEGER, GL_SHORT},
         {GL_RGBA32I, GL_RGBA_INTEGER, GL_INT},
         {GL_RGBA32UI, GL_RGBA_INTEGER, GL_UNSIGNED_INT},
         {GL_DEPTH_COMPONENT16, GL_DEPTH_COMPONENT, GL_UNSIGNED_SHORT},
         {GL_DEPTH_COMPONENT16, GL_DEPTH_COMPONENT, GL_UNSIGNED_INT},
         {GL_DEPTH_COMPONENT24, GL_DEPTH_COMPONENT, GL_UNSIGNED_INT},
         {GL_DEPTH_COMPONENT32F, GL_DEPTH_COMPONENT, GL_FLOAT},
         {GL_DEPTH24_STENCIL8, GL_DEPTH_STENCIL, GL_UNSIGNED_INT_24_8},
         {GL_DEPTH32F_STENCIL8, GL_DEPTH_STENCIL,
          GL_FLOAT_32_UNSIGNED_INT_24_8_REV},
+        // Exposed by GL_APPLE_texture_format_BGRA8888
+        {GL_BGRA8_EXT, GL_BGRA_EXT, GL_UNSIGNED_BYTE},
     };
 
     for (size_t ii = 0; ii < arraysize(kSupportedFormatTypes); ++ii) {
       supported_combinations_.insert(kSupportedFormatTypes[ii]);
     }
   }
 
   // This may be accessed from multiple threads.
   bool IsValid(GLenum internal_format, GLenum format, GLenum type) const {
     FormatType query = { internal_format, format, type };
@@ skipping 3233 matching lines @@
 uint32_t TextureManager::GetServiceIdGeneration() const {
   return current_service_id_generation_;
 }
 
 void TextureManager::IncrementServiceIdGeneration() {
   current_service_id_generation_++;
 }
 
 }  // namespace gles2
 }  // namespace gpu