Update protobuf to 3.7.1 (PR 3)

Closes bazelbuild#7611.

Change-Id: I95f61293971ce7dcf4557bf7cf2c8890544c7d31

WORKSPACE

@@ -72,8 +72,8 @@ bind(
 
 new_local_repository(
     name = "com_google_protobuf",
-    build_file = "./third_party/protobuf/3.6.1/BUILD",
-    path = "./third_party/protobuf/3.6.1/",
+    build_file = "./third_party/protobuf/3.7.1/BUILD",
+    path = "./third_party/protobuf/3.7.1/",
 )
 
 local_repository(

src/main/protobuf/BUILD

@@ -2,7 +2,7 @@ package(default_visibility = ["//visibility:public"])
 
 load("//tools/build_rules:genproto.bzl", "cc_grpc_library")
 load("//tools/build_rules:utilities.bzl", "java_library_srcs")
-load("//third_party/protobuf/3.6.1:protobuf.bzl", "py_proto_library")
+load("//third_party/protobuf/3.7.1:protobuf.bzl", "py_proto_library")
 load("//third_party/grpc:build_defs.bzl", "java_grpc_library")
 
 exports_files(

third_party/protobuf/BUILD

@@ -11,7 +11,7 @@ filegroup(
     name = "srcs",
     srcs = [
         "//third_party/protobuf/" + PROTOBUF_VERSION + ":srcs",
-        "//third_party/protobuf/" + _NEW_PROTOBUF_VERSION + ":srcs",
+        "//third_party/protobuf/" + _OLD_PROTOBUF_VERSION + ":srcs",
     ] + glob(["**"]),  # glob everything to satisfy the compile.sh srcs test
     visibility = ["//third_party:__pkg__"],
 )

third_party/protobuf/README.md

@@ -7,8 +7,8 @@ You will create and merge the following Pull Requests.
 1.  Fetch the desired protobuf version and copy it in a folder `new_proto` under
    `third_party/protobuf`.
 
-    **Example:** to upgrade to 3.6.1, download and unpack
-    [protobuf-all-3.6.1.zip](https://github.com/protocolbuffers/protobuf/releases/download/v3.6.1/protobuf-all-3.6.1.zip).
+    **Example:** to upgrade to 3.7.1, download and unpack
+    [protobuf-all-3.7.1.zip](https://github.com/protocolbuffers/protobuf/releases/download/v3.7.1/protobuf-all-3.7.1.zip).
 
 1.  Build the Java proto library from source and, in case you cloned an upstream version
     of protobuf, remove the .git folders:
@@ -103,4 +103,4 @@ You will create and merge the following Pull Requests.
 
 # Current protobuf version
 
-The current version of protobuf is [3.6.1](https://github.com/google/protobuf/releases/tag/v3.6.1).
+The current version of protobuf is [3.7.1](https://github.com/google/protobuf/releases/tag/v3.7.1).