Upgrade protobuf-java to 3.5.1

Change-Id: Ia8073e37bde88a6cd107fdc918a4c957f223cc98

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index 3ec6a28..c1cf641 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -116,8 +116,8 @@
 
 maven_jar(
     name = "protobuf",
-    artifact = "com.google.protobuf:protobuf-java:3.4.0",
-    sha1 = "b32aba0cbe737a4ca953f71688725972e3ee927c",
+    artifact = "com.google.protobuf:protobuf-java:3.5.1",
+    sha1 = "8c3492f7662fa1cbf8ca76a0f5eb1146f7725acd",
 )
 
 maven_jar(