Adding upb as submodule

upb will be used for codegen of xDS protos.

.gitmodules

@@ -51,3 +51,6 @@
 [submodule "third_party/protoc-gen-validate"]
 	path = third_party/protoc-gen-validate
 	url = https://github.com/lyft/protoc-gen-validate.git
+[submodule "third_party/upb"]
+	path = third_party/upb
+	url = https://github.com/google/upb.git

bazel/grpc_deps.bzl

@@ -8,6 +8,11 @@ def grpc_deps():
         actual = "@com_github_nanopb_nanopb//:nanopb",
     )
 
+    native.bind(
+        name = "upblib",
+        actual = "@upb//:upb",
+    )
+
     native.bind(
         name = "absl-base",
         actual = "@com_google_absl//absl/base",
@@ -184,6 +189,13 @@ def grpc_deps():
             url = "https://github.com/census-instrumentation/opencensus-cpp/archive/fdf0f308b1631bb4a942e32ba5d22536a6170274.tar.gz",
         )
 
+    if "upb" not in native.existing_rules():
+        native.http_archive(
+            name = "upb",
+            strip_prefix = "upb-9ce4a77f61c134bbed28bfd5be5cd7dc0e80f5e3",
+            url = "https://github.com/google/upb/archive/9ce4a77f61c134bbed28bfd5be5cd7dc0e80f5e3.tar.gz",
+        )
+
 
 # TODO: move some dependencies from "grpc_deps" here?
 def grpc_test_only_deps():

third_party/upb

@@ -0,0 +1 @@
+Subproject commit 9ce4a77f61c134bbed28bfd5be5cd7dc0e80f5e3

tools/run_tests/sanity/check_bazel_workspace.py

@@ -42,6 +42,7 @@ _ZOPEFOUNDATION_ZOPE_INTERFACE_DEP_NAME = 'com_github_zopefoundation_zope_interf
 _TWISTED_CONSTANTLY_DEP_NAME = 'com_github_twisted_constantly'
 
 _GRPC_DEP_NAMES = [
+    'upb',
     'boringssl',
     'com_github_madler_zlib',
     'com_google_protobuf',

tools/run_tests/sanity/check_submodules.sh

@@ -40,6 +40,7 @@ cat << EOF | awk '{ print $1 }' | sort > "$want_submodules"
  9245d481eb3e890f708ff2d7dadf2a10c04748ba third_party/libcxxabi (heads/release_60)
  48cb18e5c419ddd23d9badcfe4e9df7bde1979b2 third_party/protobuf (v3.6.0.1-37-g48cb18e5)
  e143189bf6f37b3957fb31743df6a1bcf4a8c685 third_party/protoc-gen-validate (v0.0.10)
+ 9ce4a77f61c134bbed28bfd5be5cd7dc0e80f5e3 third_party/upb (heads/upbc-cpp)
  cacf7f1d4e3d44d871b605da3b647f07d718623f third_party/zlib (v1.2.11)
 EOF