Move our runtime to proto3 and make the dependency explicit

gRPC.podspec

@@ -67,7 +67,8 @@ Pod::Spec.new do |s|
 
   s.subspec 'GRPCClient' do |gs|
     gs.summary = 'Objective-C wrapper around the core gRPC library.'
-    gs.authors  = { 'Jorge Canizales' => 'jcanizales@google.com' }
+    gs.authors  = { 'Jorge Canizales' => 'jcanizales@google.com',
+                    'Michael Lumish'  => 'mlumish@google.com' }
 
     gs.source_files = 'src/objective-c/GRPCClient/*.{h,m}',
                       'src/objective-c/GRPCClient/private/*.{h,m}'
@@ -90,5 +91,6 @@ Pod::Spec.new do |s|
 
     ps.dependency 'gRPC/GRPCClient'
     ps.dependency 'gRPC/RxLibrary'
+    ps.dependency 'Protobuf', '~> 3.0'
   end
 end

src/objective-c/ProtoRPC/ProtoRPC.m

@@ -36,7 +36,7 @@
 #import <gRPC/GRXWriteable.h>
 #import <gRPC/GRXWriter.h>
 #import <gRPC/GRXWriter+Transformations.h>
-#import <ProtocolBuffers/ProtocolBuffers.h>
+#import <Protobuf/GPBProtocolBuffers.h>
 
 @implementation ProtoRPC {
   id<GRXWriteable> _responseWriteable;
@@ -65,7 +65,7 @@
   }
   // A writer that serializes the proto messages to send.
   id<GRXWriter> bytesWriter =
-      [[[GRXWriter alloc] initWithWriter:requestsWriter] map:^id(PBGeneratedMessage *proto) {
+      [[[GRXWriter alloc] initWithWriter:requestsWriter] map:^id(GPBMessage *proto) {
         return [proto data];
       }];
   if ((self = [super initWithHost:host method:method requestsWriter:bytesWriter])) {