Fixes needed to make roll-forward of StartCall and corking work

Author: vjpai

BUILD

@@ -124,6 +124,7 @@ GRPC_SECURE_PUBLIC_HDRS = [
 # TODO(ctiller): layer grpc atop grpc_unsecure, layer grpc++ atop grpc++_unsecure
 GRPCXX_SRCS = [
     "src/cpp/client/channel_cc.cc",
+    "src/cpp/client/client_callback.cc",
     "src/cpp/client/client_context.cc",
     "src/cpp/client/client_interceptor.cc",
     "src/cpp/client/create_channel.cc",

BUILD.gn

@@ -1220,6 +1220,7 @@ config("grpc_config") {
         "include/grpcpp/support/time.h",
         "include/grpcpp/support/validate_service_config.h",
         "src/cpp/client/channel_cc.cc",
+        "src/cpp/client/client_callback.cc",
         "src/cpp/client/client_context.cc",
         "src/cpp/client/client_interceptor.cc",
         "src/cpp/client/create_channel.cc",

CMakeLists.txt

@@ -2482,6 +2482,7 @@ endif()
 
 add_library(grpc++
   src/cpp/client/channel_cc.cc
+  src/cpp/client/client_callback.cc
   src/cpp/client/client_context.cc
   src/cpp/client/client_interceptor.cc
   src/cpp/client/create_channel.cc
@@ -3183,6 +3184,7 @@ endif()
 
 add_library(grpc++_unsecure
   src/cpp/client/channel_cc.cc
+  src/cpp/client/client_callback.cc
   src/cpp/client/client_context.cc
   src/cpp/client/client_interceptor.cc
   src/cpp/client/create_channel.cc

Makefile

@@ -4717,6 +4717,7 @@ $(OBJDIR)/$(CONFIG)/test/cpp/microbenchmarks/helpers.o: $(GENDIR)/src/proto/grpc
 
 LIBGRPC++_SRC = \
     src/cpp/client/channel_cc.cc \
+    src/cpp/client/client_callback.cc \
     src/cpp/client/client_context.cc \
     src/cpp/client/client_interceptor.cc \
     src/cpp/client/create_channel.cc \
@@ -5423,6 +5424,7 @@ endif
 
 LIBGRPC++_UNSECURE_SRC = \
     src/cpp/client/channel_cc.cc \
+    src/cpp/client/client_callback.cc \
     src/cpp/client/client_context.cc \
     src/cpp/client/client_interceptor.cc \
     src/cpp/client/create_channel.cc \

build_autogenerated.yaml

@@ -2203,6 +2203,7 @@ libs:
   - src/cpp/thread_manager/thread_manager.h
   src:
   - src/cpp/client/channel_cc.cc
+  - src/cpp/client/client_callback.cc
   - src/cpp/client/client_context.cc
   - src/cpp/client/client_interceptor.cc
   - src/cpp/client/create_channel.cc
@@ -2592,6 +2593,7 @@ libs:
   - src/cpp/thread_manager/thread_manager.h
   src:
   - src/cpp/client/channel_cc.cc
+  - src/cpp/client/client_callback.cc
   - src/cpp/client/client_context.cc
   - src/cpp/client/client_interceptor.cc
   - src/cpp/client/create_channel.cc

gRPC-C++.podspec

@@ -616,6 +616,7 @@ Pod::Spec.new do |s|
                       'src/core/tsi/transport_security_grpc.h',
                       'src/core/tsi/transport_security_interface.h',
                       'src/cpp/client/channel_cc.cc',
+                      'src/cpp/client/client_callback.cc',
                       'src/cpp/client/client_context.cc',
                       'src/cpp/client/client_interceptor.cc',
                       'src/cpp/client/create_channel.cc',

grpc.gyp

@@ -1313,6 +1313,7 @@
       ],
       'sources': [
         'src/cpp/client/channel_cc.cc',
+        'src/cpp/client/client_callback.cc',
         'src/cpp/client/client_context.cc',
         'src/cpp/client/client_interceptor.cc',
         'src/cpp/client/create_channel.cc',
@@ -1464,6 +1465,7 @@
       ],
       'sources': [
         'src/cpp/client/channel_cc.cc',
+        'src/cpp/client/client_callback.cc',
         'src/cpp/client/client_context.cc',
         'src/cpp/client/client_interceptor.cc',
         'src/cpp/client/create_channel.cc',