Bump protobuf runtime dependency versions

src/csharp/Grpc.Core/Version.csproj.include

@@ -2,6 +2,6 @@
 <Project>
   <PropertyGroup>
     <GrpcCsharpVersion>1.12.0-dev</GrpcCsharpVersion>
-    <GoogleProtobufVersion>3.3.0</GoogleProtobufVersion>
+    <GoogleProtobufVersion>3.5.1</GoogleProtobufVersion>
   </PropertyGroup>
 </Project>

src/python/grpcio_health_checking/setup.py

@@ -57,7 +57,7 @@ PACKAGE_DIRECTORIES = {
 }
 
 INSTALL_REQUIRES = (
-    'protobuf>=3.5.0.post1',
+    'protobuf>=3.5.2.post1',
     'grpcio>={version}'.format(version=grpc_version.VERSION),
 )
 

src/python/grpcio_reflection/setup.py

@@ -58,7 +58,7 @@ PACKAGE_DIRECTORIES = {
 }
 
 INSTALL_REQUIRES = (
-    'protobuf>=3.5.0.post1',
+    'protobuf>=3.5.2.post1',
     'grpcio>={version}'.format(version=grpc_version.VERSION),
 )
 

src/python/grpcio_testing/setup.py

@@ -29,7 +29,7 @@ PACKAGE_DIRECTORIES = {
 }
 
 INSTALL_REQUIRES = (
-    'protobuf>=3.5.0.post1',
+    'protobuf>=3.5.2.post1',
     'grpcio>={version}'.format(version=grpc_version.VERSION),
 )
 

src/python/grpcio_tests/setup.py

@@ -41,7 +41,7 @@ INSTALL_REQUIRES = (
     'grpcio>={version}'.format(version=grpc_version.VERSION),
     'grpcio-tools>={version}'.format(version=grpc_version.VERSION),
     'grpcio-health-checking>={version}'.format(version=grpc_version.VERSION),
-    'oauth2client>=1.4.7', 'protobuf>=3.5.0.post1', 'six>=1.10',
+    'oauth2client>=1.4.7', 'protobuf>=3.5.2.post1', 'six>=1.10',
     'google-auth>=1.0.0', 'requests>=2.14.2')
 
 COMMAND_CLASS = {

templates/src/csharp/Grpc.Core/Version.csproj.include.template

@@ -4,6 +4,6 @@
   <Project>
     <PropertyGroup>
       <GrpcCsharpVersion>${settings.csharp_version}</GrpcCsharpVersion>
-      <GoogleProtobufVersion>3.3.0</GoogleProtobufVersion>
+      <GoogleProtobufVersion>3.5.1</GoogleProtobufVersion>
     </PropertyGroup>
   </Project>