Save interface block infomation to program cache.

gpu/command_buffer/service/disk_cache_proto.proto

 syntax = "proto2";
 option optimize_for = LITE_RUNTIME;
 
 message ShaderVariableProto {
   optional uint32 type = 1;
   optional uint32 precision = 2;
   optional string name = 3;
   optional string mapped_name = 4;
   optional uint32 array_size = 5;
   optional bool static_use = 6;
@@ skipping 14 matching lines @@
   optional ShaderVariableProto basic = 1;
   optional int32 interpolation = 2;
   optional bool is_invariant = 3;
 }
 
 message ShaderOutputVariableProto {
   optional ShaderVariableProto basic = 1;
   optional int32 location = 2;
 }
 
+message ShaderInterfaceBlockFieldProto {
+  optional ShaderVariableProto basic = 1;
+  optional bool is_row_major_layout = 2;
+}
+
+message ShaderInterfaceBlockProto {
+  optional string name = 1;
+  optional string mapped_name = 2;
+  optional string instance_name = 3;
+  optional uint32 array_size = 4;

[xinghua.cao, 2016/05/30 09:55:46]

variable 'layout' type is sh::BlockLayoutType(enum define in angle), I cannot
conform that proto buffer could reference C++ type, so cast it to int32. It
maybe an error. Please help to check it. 

[qiankun, 2016/05/30 12:42:11]

I think you can define same enum in proto file.

[xinghua.cao, 2016/05/31 06:09:10]

If I define a same enum type in proto file, the namespaces are different, it
cannot pass when building.

+  optional int32 layout = 5;
+  optional bool is_row_major_layout = 6;
+  optional bool static_use = 7;
+  repeated ShaderInterfaceBlockFieldProto fields = 8;
+}
+
 message ShaderProto {
   optional bytes sha = 1;
   repeated ShaderAttributeProto attribs = 2;
   repeated ShaderUniformProto uniforms = 3;
   repeated ShaderVaryingProto varyings = 4;
   repeated ShaderOutputVariableProto output_variables = 5;
+  repeated ShaderInterfaceBlockProto interface_blocks = 6;
 }
 
 message GpuProgramProto {
   optional bytes sha = 1;
   optional uint32 format = 2;
   optional bytes program = 3;
 
   optional ShaderProto vertex_shader = 4;
   optional ShaderProto fragment_shader = 5;
 }