Handle compressed textures allocated via TexStorage2D.

gpu/command_buffer/common/gles2_cmd_utils.h

Index: gpu/command_buffer/common/gles2_cmd_utils.h
diff --git a/gpu/command_buffer/common/gles2_cmd_utils.h b/gpu/command_buffer/common/gles2_cmd_utils.h
index 9104fcd68b9dfc7d8b14d94dfb13749598a40d74..1623b4b429fb5fcd4c7b3769520cb8f2b75edcfe 100644
--- a/gpu/command_buffer/common/gles2_cmd_utils.h
+++ b/gpu/command_buffer/common/gles2_cmd_utils.h
@@ -146,6 +146,8 @@ class GLES2_UTILS_EXPORT GLES2Util {
       uint32_t* opt_padded_row_size, uint32_t* opt_skip_size,
       uint32_t* opt_padding);
 
+  static bool IsCompressedTextureFormat(int internal_format);

[Zhenyao Mo, 2016/04/28 17:57:12]

You don't have to redefined this function.  We already have
FeatureInfo::validators()->compressed_texture_format, which contains all the
allowed compressed texture formats. You can just use it in the decoder. It's
better if in the future when we add new extensions, we don't have to also update
the duplicated table here.

[Ken Russell (switch to Gerrit), 2016/04/29 13:10:06]

Thanks for pointing this out. It's necessary to call this both from the
GLES2Decoder as well as the TextureManager, but since the TextureManager already
accesses the decoder, it's best to just put it in the decoder. Done.

+
   static size_t RenderbufferBytesPerPixel(int format);
 
   // Return the element's number of bytes.