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

gpu/command_buffer/service/texture_manager.cc

Index: gpu/command_buffer/service/texture_manager.cc
diff --git a/gpu/command_buffer/service/texture_manager.cc b/gpu/command_buffer/service/texture_manager.cc
index f6a75dd40e91325cd5bc88ee00c8f5b83fb822d3..8f5f5b7ed85f1d31aa0d35d9b6a4900b3bae5c5b 100644
--- a/gpu/command_buffer/service/texture_manager.cc
+++ b/gpu/command_buffer/service/texture_manager.cc
@@ -152,6 +152,7 @@ class FormatTypeValidator {
         {GL_SRGB_ALPHA, GL_SRGB_ALPHA, GL_UNSIGNED_BYTE},
         // Exposed by GL_EXT_texture_format_BGRA8888
         {GL_BGRA_EXT, GL_BGRA_EXT, GL_UNSIGNED_BYTE},
+        {GL_BGRA8_EXT, GL_BGRA_EXT, GL_UNSIGNED_BYTE},
         // Exposed by GL_EXT_texture_rg
         {GL_RED, GL_RED, GL_UNSIGNED_BYTE},
         {GL_RG, GL_RG, GL_UNSIGNED_BYTE},
@@ -761,7 +762,10 @@ bool Texture::TextureFilterable(const FeatureInfo* feature_info,
                                 GLenum internal_format,
                                 GLenum type) {
   if (feature_info->validators()->texture_unsized_internal_format.IsValid(
-      internal_format)) {
+          internal_format) ||
+      feature_info->validators()
+          ->texture_sized_color_renderable_internal_format.IsValid(
+              internal_format)) {
     switch (type) {
       case GL_FLOAT:
         return feature_info->feature_flags().enable_texture_float_linear;