Add a base mipmap level walkaround for Intel MacOSX

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 3895c9f7b023467215c13843320cba7d1079154e..ef60dab4f84667e3578ed7f49359e4afe2077587 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -15698,6 +15698,12 @@ void GLES2DecoderImpl::TexStorageImpl(GLenum target,
     compatibility_internal_format = format_info->decompressed_internal_format;
   }
 
+  GLint base_level = 0;

[Zhenyao Mo, 2016/08/25 18:06:55]

You should just use texture->base_level(), and no need to query the driver
later.

+  if (feature_info_->workarounds().reset_base_mipmap_level_before_texstorage) {
+    glGetTexParameteriv(target, GL_TEXTURE_BASE_LEVEL, &base_level);
+    if (base_level > 0)
+      glTexParameteri(target, GL_TEXTURE_BASE_LEVEL, 0);
+  }
   // TODO(zmo): We might need to emulate TexStorage using TexImage or
   // CompressedTexImage on Mac OSX where we expose ES3 APIs when the underlying
   // driver is lower than 4.2 and ARB_texture_storage extension doesn't exist.
@@ -15708,6 +15714,9 @@ void GLES2DecoderImpl::TexStorageImpl(GLenum target,
     glTexStorage3D(target, levels, compatibility_internal_format, width, height,
                    depth);
   }
+  if (feature_info_->workarounds().reset_base_mipmap_level_before_texstorage &&
+      base_level > 0)
+      glTexParameteri(target, GL_TEXTURE_BASE_LEVEL, base_level);
 
   {
     GLsizei level_width = width;