Upgrade protobuf-java to 3.4.0

Change-Id: I8941d1bbe1c2ae5feef59309b186445a37150dd1

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index 1122bcf..d1faf89 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -116,8 +116,8 @@
 
 maven_jar(
     name = "protobuf",
-    artifact = "com.google.protobuf:protobuf-java:3.0.0-beta-2",
-    sha1 = "de80fe047052445869b96f6def6baca7182c95af",
+    artifact = "com.google.protobuf:protobuf-java:3.4.0",
+    sha1 = "b32aba0cbe737a4ca953f71688725972e3ee927c",
 )
 
 maven_jar(