grpc_deps() takes care of protobuf.

src/WORKSPACE

@@ -44,32 +44,6 @@ load("@com_github_grpc_grpc//bazel:grpc_deps.bzl", "grpc_deps")
 
 grpc_deps()
 
-# proto_library rules implicitly depend on @com_google_protobuf//:protoc,
-# which is the proto-compiler.
-# This statement defines the @com_google_protobuf repo.
-http_archive(
-    name = "com_google_protobuf",
-    sha256 = "73fdad358857e120fd0fa19e071a96e15c0f23bb25f85d3f7009abfd4f264a2a",
-    strip_prefix = "protobuf-3.6.1.3",
-    urls = ["https://github.com/google/protobuf/archive/v3.6.1.3.tar.gz"],
-)
-
-http_archive(
-    name = "com_google_protobuf_cc",
-    sha256 = "73fdad358857e120fd0fa19e071a96e15c0f23bb25f85d3f7009abfd4f264a2a",
-    strip_prefix = "protobuf-3.6.1.3",
-    urls = ["https://github.com/google/protobuf/archive/v3.6.1.3.tar.gz"],
-)
-
-# java_proto_library rules implicitly depend on @com_google_protobuf_java//:java_toolchain,
-# which is the Java proto runtime (base classes and common utilities).
-http_archive(
-    name = "com_google_protobuf_java",
-    sha256 = "73fdad358857e120fd0fa19e071a96e15c0f23bb25f85d3f7009abfd4f264a2a",
-    strip_prefix = "protobuf-3.6.1.3",
-    urls = ["https://github.com/google/protobuf/archive/v3.6.1.3.tar.gz"],
-)
-
 # go rules related
 git_repository(
     name = "io_bazel_rules_go",