gles2: Fix glDiscardFramebufferEXT

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 e7be28a03bc3b55679882e6bb429ca75230e5f8e..f7dbbbf31693b4bd66aaf29bf11f9f55914a7166 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -5959,7 +5959,13 @@ void GLES2DecoderImpl::InvalidateFramebufferImpl(
     validated_attachments[validated_count++] = attachment;
   }
   if (invalidate_depth && invalidate_stencil) {
-    validated_attachments[validated_count++] = GL_DEPTH_STENCIL_ATTACHMENT;
+    if (op != kFramebufferDiscard || gl_version_info().is_es3) {
+      validated_attachments[validated_count++] = GL_DEPTH_STENCIL_ATTACHMENT;
+    } else {
+      // DEPTH_STENCIL is not a valid token for glDiscardFramebufferEXT
+      validated_attachments[validated_count++] = GL_DEPTH_ATTACHMENT;
+      validated_attachments[validated_count++] = GL_STENCIL_ATTACHMENT;

[Zhenyao Mo, 2016/12/19 17:53:48]

It's easier to always split to DEPTH_ATTACHMENT and STENCIL_ATTACHMENT here,
because in ES3 DEPTH_STENCIL_ATTACHMENT is just an alias for DEPTH_ATTACHMENT +
STENCIL_ATTACHMENT.

[jbriance, 2016/12/19 19:40:45]

Done in patch set 3

+    }
   }
 
   // If the default framebuffer is bound but we are still rendering to an