all: update to proto 3.4.0

.travis.yml

@@ -5,7 +5,7 @@ language: java
 env:
   global:
     - GRADLE_OPTS=-Xmx512m
-    - PROTOBUF_VERSION=3.3.1
+    - PROTOBUF_VERSION=3.4.0
     - LDFLAGS=-L/tmp/protobuf/lib
     - CXXFLAGS=-I/tmp/protobuf/include
     - LD_LIBRARY_PATH=/tmp/protobuf/lib

COMPILING.md

@@ -33,7 +33,7 @@ For Linux, Mac and MinGW:
 ```
 $ git clone https://github.com/google/protobuf.git
 $ cd protobuf
-$ git checkout v3.3.1
+$ git checkout v3.4.0
 $ ./autogen.sh
 $ ./configure
 $ make
@@ -72,16 +72,16 @@ When building on Windows and VC++, you need to specify project properties for
 Gradle to find protobuf:
 ```
 .\gradlew install ^
-    -PvcProtobufInclude=C:\path\to\protobuf-3.3.1\src ^
-    -PvcProtobufLibs=C:\path\to\protobuf-3.3.1\vsprojects\Release ^
+    -PvcProtobufInclude=C:\path\to\protobuf-3.4.0\src ^
+    -PvcProtobufLibs=C:\path\to\protobuf-3.4.0\vsprojects\Release ^
     -PtargetArch=x86_32
 ```
 
 Since specifying those properties every build is bothersome, you can instead
 create ``<project-root>\gradle.properties`` with contents like:
 ```
-vcProtobufInclude=C:\\path\\to\\protobuf-3.3.1\\src
-vcProtobufLibs=C:\\path\\to\\protobuf-3.3.1\\vsprojects\\Release
+vcProtobufInclude=C:\\path\\to\\protobuf-3.4.0\\src
+vcProtobufLibs=C:\\path\\to\\protobuf-3.4.0\\vsprojects\\Release
 targetArch=x86_32
 ```
 

android-interop-testing/app/build.gradle

@@ -29,7 +29,7 @@ android {
 
 protobuf {
     protoc {
-        artifact = 'com.google.protobuf:protoc:3.3.0'
+        artifact = 'com.google.protobuf:protoc:3.4.0'
     }
     plugins {
         grpc {