Save interface block infomation to program cache.

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 6d78f4b9146fd403bb694c8f04522636277fd0e0..b1f47fe5238aed92214b213509ea47dc42cfc260 100644
--- a/gpu/command_buffer/service/disk_cache_proto.proto
+++ b/gpu/command_buffer/service/disk_cache_proto.proto
@@ -32,12 +32,29 @@ message ShaderOutputVariableProto {
   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 {