Work around CopyTexImage2D issue on Intel Mac OSX 10.12

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 fad05fe6ff9d4458c167d167cc854ca3fcf09400..dcf4d739423b909eb6b12ca64a5f83bdfe044b24 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -13314,6 +13314,18 @@ void GLES2DecoderImpl::DoCopyTexImage2D(
   } else {
     GLenum final_internal_format = TextureManager::AdjustTexInternalFormat(
         feature_info_.get(), internal_format);
+    if (workarounds().init_cube_map_before_copyteximage &&
+        texture->target() == GL_TEXTURE_CUBE_MAP &&
+        target != GL_TEXTURE_CUBE_MAP_POSITIVE_X) {
+      for (int i = 0; i < 2; ++i) {
+        TextureManager::DoTexImageArguments args = {
+          target, i, final_internal_format, 1, 1, 1, border,
+          format, type, nullptr, 1, 0,
+          TextureManager::DoTexImageArguments::kTexImage2D };
+        texture_manager()->WorkaroundCopyTexImageCubeMap(&texture_state_,
+            &state_, &framebuffer_state_, texture_ref, func_name, args);
+      }

[Zhenyao Mo, 2016/09/28 21:14:23]

This gets complicated when we also need to emulate for LUMINANCE_ALPHA formats.

Could you at least add a TODO and create a bug to track it?

[qiankun, 2016/09/29 00:51:27]

What kinds of TODO, something like to handle this workaround and LUMINANCE_ALPHA
emulation correctly?

[Zhenyao Mo, 2016/09/29 20:30:16]

What I mean is, if the src texture format is LUMINANCE/ALPHA, then
WorkaroundCopyTexImageCubeMap() will generate GL errors on platforms where these
formats are not supported.

[qiankun, 2016/09/30 05:47:39]

Sorry, I didn't get this. Can you explain it further? Where does the GL errors
come from? I think WorkaroundCopyTexImageCubeMap doens't use src texture format.
Does LUMINANCE/ALPHA emulation patch land chromium already?

[qiankun, 2016/10/11 01:56:20]

Zhenyao&Ken, do I still need to add this TODO according my last comment as
below:

Format is also mapped when doing glTexImage2D, see:
https://cs.chromium.org/chromium/src/gpu/command_buffer/service/texture_manag...

+    }
 
     // The service id and target of the texture attached to READ_FRAMEBUFFER.
     GLuint source_texture_service_id = 0;