command_buffer: Implement EXT_blend_func_extended

gpu/command_buffer/service/disk_cache_proto.proto

Index: gpu/command_buffer/service/disk_cache_proto.proto
diff --git a/gpu/command_buffer/service/disk_cache_proto.proto b/gpu/command_buffer/service/disk_cache_proto.proto
index b1059a6338694f59e2587294c6530a69ba545568..05c6ea0404c67345142f225021c84d1316c74908 100644
--- a/gpu/command_buffer/service/disk_cache_proto.proto
+++ b/gpu/command_buffer/service/disk_cache_proto.proto
@@ -32,6 +32,7 @@ message ShaderProto {
   repeated ShaderAttributeProto attribs = 2;
   repeated ShaderUniformProto uniforms = 3;
   repeated ShaderVaryingProto varyings = 4;
+  repeated ShaderAttributeProto output_variables = 5;

[Zhenyao Mo, 2015/08/31 21:12:30]

Have you verified what are the returned values for ShGetOutputVariables() in
ES2? Are they empty or gl_FragColor/gl_FragData?

[Kimmo Kinnunen, 2015/09/24 13:16:27]

Yeah, I implemented it in ANGLE for purposes of this patch.

For vertex shaders, it's empty. I can fix it to be whatever you want, if we need
vertex outputs for consistency.

For fragment shaders, it might contain gl_FragColor, gl_FragData,
gl_SecondaryFragColor, gl_SecondaryFragData, gl_FragDepthEXT.

[Zhenyao Mo, 2015/09/30 00:23:47]

Sounds good.

 }
 
 message GpuProgramProto {