Backoff test is now a C++ file
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 77b60e8..f39647a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -379,7 +379,6 @@
 add_dependencies(buildtests_c alloc_test)
 add_dependencies(buildtests_c alpn_test)
 add_dependencies(buildtests_c arena_test)
-add_dependencies(buildtests_c backoff_test)
 add_dependencies(buildtests_c bad_server_response_test)
 add_dependencies(buildtests_c bin_decoder_test)
 add_dependencies(buildtests_c bin_encoder_test)
@@ -633,6 +632,7 @@
 add_dependencies(buildtests_cxx alarm_cpp_test)
 add_dependencies(buildtests_cxx async_end2end_test)
 add_dependencies(buildtests_cxx auth_property_iterator_test)
+add_dependencies(buildtests_cxx backoff_test)
 add_dependencies(buildtests_cxx bdp_estimator_test)
 if(_gRPC_PLATFORM_LINUX OR _gRPC_PLATFORM_MAC OR _gRPC_PLATFORM_POSIX)
 add_dependencies(buildtests_cxx bm_arena)
@@ -5206,36 +5206,6 @@
 endif (gRPC_BUILD_TESTS)
 if (gRPC_BUILD_TESTS)
 
-add_executable(backoff_test
-  test/core/backoff/backoff_test.cc
-)
-
-
-target_include_directories(backoff_test
-  PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}
-  PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/include
-  PRIVATE ${BORINGSSL_ROOT_DIR}/include
-  PRIVATE ${PROTOBUF_ROOT_DIR}/src
-  PRIVATE ${BENCHMARK_ROOT_DIR}/include
-  PRIVATE ${ZLIB_ROOT_DIR}
-  PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/third_party/zlib
-  PRIVATE ${CARES_INCLUDE_DIR}
-  PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/third_party/cares/cares
-  PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/third_party/gflags/include
-  PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/third_party/abseil-cpp
-)
-
-target_link_libraries(backoff_test
-  ${_gRPC_ALLTARGETS_LIBRARIES}
-  grpc_test_util
-  grpc
-  gpr_test_util
-  gpr
-)
-
-endif (gRPC_BUILD_TESTS)
-if (gRPC_BUILD_TESTS)
-
 add_executable(bad_server_response_test
   test/core/end2end/bad_server_response_test.cc
 )
@@ -9305,6 +9275,45 @@
 endif (gRPC_BUILD_TESTS)
 if (gRPC_BUILD_TESTS)
 
+add_executable(backoff_test
+  test/core/backoff/backoff_test.cc
+  third_party/googletest/googletest/src/gtest-all.cc
+  third_party/googletest/googlemock/src/gmock-all.cc
+)
+
+
+target_include_directories(backoff_test
+  PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}
+  PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/include
+  PRIVATE ${BORINGSSL_ROOT_DIR}/include
+  PRIVATE ${PROTOBUF_ROOT_DIR}/src
+  PRIVATE ${BENCHMARK_ROOT_DIR}/include
+  PRIVATE ${ZLIB_ROOT_DIR}
+  PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/third_party/zlib
+  PRIVATE ${CARES_INCLUDE_DIR}
+  PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/third_party/cares/cares
+  PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/third_party/gflags/include
+  PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/third_party/abseil-cpp
+  PRIVATE third_party/googletest/googletest/include
+  PRIVATE third_party/googletest/googletest
+  PRIVATE third_party/googletest/googlemock/include
+  PRIVATE third_party/googletest/googlemock
+  PRIVATE ${_gRPC_PROTO_GENS_DIR}
+)
+
+target_link_libraries(backoff_test
+  ${_gRPC_PROTOBUF_LIBRARIES}
+  ${_gRPC_ALLTARGETS_LIBRARIES}
+  grpc_test_util
+  grpc
+  gpr_test_util
+  gpr
+  ${_gRPC_GFLAGS_LIBRARIES}
+)
+
+endif (gRPC_BUILD_TESTS)
+if (gRPC_BUILD_TESTS)
+
 add_executable(bdp_estimator_test
   test/core/transport/bdp_estimator_test.cc
   third_party/googletest/googletest/src/gtest-all.cc
diff --git a/Makefile b/Makefile
index c85b1bc..1ed10cd 100644
--- a/Makefile
+++ b/Makefile
@@ -951,7 +951,6 @@
 alpn_test: $(BINDIR)/$(CONFIG)/alpn_test
 api_fuzzer: $(BINDIR)/$(CONFIG)/api_fuzzer
 arena_test: $(BINDIR)/$(CONFIG)/arena_test
-backoff_test: $(BINDIR)/$(CONFIG)/backoff_test
 bad_server_response_test: $(BINDIR)/$(CONFIG)/bad_server_response_test
 bin_decoder_test: $(BINDIR)/$(CONFIG)/bin_decoder_test
 bin_encoder_test: $(BINDIR)/$(CONFIG)/bin_encoder_test
@@ -1098,6 +1097,7 @@
 alarm_cpp_test: $(BINDIR)/$(CONFIG)/alarm_cpp_test
 async_end2end_test: $(BINDIR)/$(CONFIG)/async_end2end_test
 auth_property_iterator_test: $(BINDIR)/$(CONFIG)/auth_property_iterator_test
+backoff_test: $(BINDIR)/$(CONFIG)/backoff_test
 bdp_estimator_test: $(BINDIR)/$(CONFIG)/bdp_estimator_test
 bm_arena: $(BINDIR)/$(CONFIG)/bm_arena
 bm_call_create: $(BINDIR)/$(CONFIG)/bm_call_create
@@ -1351,7 +1351,6 @@
   $(BINDIR)/$(CONFIG)/alloc_test \
   $(BINDIR)/$(CONFIG)/alpn_test \
   $(BINDIR)/$(CONFIG)/arena_test \
-  $(BINDIR)/$(CONFIG)/backoff_test \
   $(BINDIR)/$(CONFIG)/bad_server_response_test \
   $(BINDIR)/$(CONFIG)/bin_decoder_test \
   $(BINDIR)/$(CONFIG)/bin_encoder_test \
@@ -1541,6 +1540,7 @@
   $(BINDIR)/$(CONFIG)/alarm_cpp_test \
   $(BINDIR)/$(CONFIG)/async_end2end_test \
   $(BINDIR)/$(CONFIG)/auth_property_iterator_test \
+  $(BINDIR)/$(CONFIG)/backoff_test \
   $(BINDIR)/$(CONFIG)/bdp_estimator_test \
   $(BINDIR)/$(CONFIG)/bm_arena \
   $(BINDIR)/$(CONFIG)/bm_call_create \
@@ -1667,6 +1667,7 @@
   $(BINDIR)/$(CONFIG)/alarm_cpp_test \
   $(BINDIR)/$(CONFIG)/async_end2end_test \
   $(BINDIR)/$(CONFIG)/auth_property_iterator_test \
+  $(BINDIR)/$(CONFIG)/backoff_test \
   $(BINDIR)/$(CONFIG)/bdp_estimator_test \
   $(BINDIR)/$(CONFIG)/bm_arena \
   $(BINDIR)/$(CONFIG)/bm_call_create \
@@ -1768,8 +1769,6 @@
 	$(Q) $(BINDIR)/$(CONFIG)/alpn_test || ( echo test alpn_test failed ; exit 1 )
 	$(E) "[RUN]     Testing arena_test"
 	$(Q) $(BINDIR)/$(CONFIG)/arena_test || ( echo test arena_test failed ; exit 1 )
-	$(E) "[RUN]     Testing backoff_test"
-	$(Q) $(BINDIR)/$(CONFIG)/backoff_test || ( echo test backoff_test failed ; exit 1 )
 	$(E) "[RUN]     Testing bad_server_response_test"
 	$(Q) $(BINDIR)/$(CONFIG)/bad_server_response_test || ( echo test bad_server_response_test failed ; exit 1 )
 	$(E) "[RUN]     Testing bin_decoder_test"
@@ -2036,6 +2035,8 @@
 	$(Q) $(BINDIR)/$(CONFIG)/async_end2end_test || ( echo test async_end2end_test failed ; exit 1 )
 	$(E) "[RUN]     Testing auth_property_iterator_test"
 	$(Q) $(BINDIR)/$(CONFIG)/auth_property_iterator_test || ( echo test auth_property_iterator_test failed ; exit 1 )
+	$(E) "[RUN]     Testing backoff_test"
+	$(Q) $(BINDIR)/$(CONFIG)/backoff_test || ( echo test backoff_test failed ; exit 1 )
 	$(E) "[RUN]     Testing bdp_estimator_test"
 	$(Q) $(BINDIR)/$(CONFIG)/bdp_estimator_test || ( echo test bdp_estimator_test failed ; exit 1 )
 	$(E) "[RUN]     Testing bm_arena"
@@ -8879,38 +8880,6 @@
 endif
 
 
-BACKOFF_TEST_SRC = \
-    test/core/backoff/backoff_test.cc \
-
-BACKOFF_TEST_OBJS = $(addprefix $(OBJDIR)/$(CONFIG)/, $(addsuffix .o, $(basename $(BACKOFF_TEST_SRC))))
-ifeq ($(NO_SECURE),true)
-
-# You can't build secure targets if you don't have OpenSSL.
-
-$(BINDIR)/$(CONFIG)/backoff_test: openssl_dep_error
-
-else
-
-
-
-$(BINDIR)/$(CONFIG)/backoff_test: $(BACKOFF_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
-	$(E) "[LD]      Linking $@"
-	$(Q) mkdir -p `dirname $@`
-	$(Q) $(LD) $(LDFLAGS) $(BACKOFF_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LDLIBS) $(LDLIBS_SECURE) -o $(BINDIR)/$(CONFIG)/backoff_test
-
-endif
-
-$(OBJDIR)/$(CONFIG)/test/core/backoff/backoff_test.o:  $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
-
-deps_backoff_test: $(BACKOFF_TEST_OBJS:.o=.dep)
-
-ifneq ($(NO_SECURE),true)
-ifneq ($(NO_DEPS),true)
--include $(BACKOFF_TEST_OBJS:.o=.dep)
-endif
-endif
-
-
 BAD_SERVER_RESPONSE_TEST_SRC = \
     test/core/end2end/bad_server_response_test.cc \
 
@@ -13628,6 +13597,49 @@
 endif
 
 
+BACKOFF_TEST_SRC = \
+    test/core/backoff/backoff_test.cc \
+
+BACKOFF_TEST_OBJS = $(addprefix $(OBJDIR)/$(CONFIG)/, $(addsuffix .o, $(basename $(BACKOFF_TEST_SRC))))
+ifeq ($(NO_SECURE),true)
+
+# You can't build secure targets if you don't have OpenSSL.
+
+$(BINDIR)/$(CONFIG)/backoff_test: openssl_dep_error
+
+else
+
+
+
+
+ifeq ($(NO_PROTOBUF),true)
+
+# You can't build the protoc plugins or protobuf-enabled targets if you don't have protobuf 3.0.0+.
+
+$(BINDIR)/$(CONFIG)/backoff_test: protobuf_dep_error
+
+else
+
+$(BINDIR)/$(CONFIG)/backoff_test: $(PROTOBUF_DEP) $(BACKOFF_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
+	$(E) "[LD]      Linking $@"
+	$(Q) mkdir -p `dirname $@`
+	$(Q) $(LDXX) $(LDFLAGS) $(BACKOFF_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LDLIBSXX) $(LDLIBS_PROTOBUF) $(LDLIBS) $(LDLIBS_SECURE) $(GTEST_LIB) -o $(BINDIR)/$(CONFIG)/backoff_test
+
+endif
+
+endif
+
+$(OBJDIR)/$(CONFIG)/test/core/backoff/backoff_test.o:  $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
+
+deps_backoff_test: $(BACKOFF_TEST_OBJS:.o=.dep)
+
+ifneq ($(NO_SECURE),true)
+ifneq ($(NO_DEPS),true)
+-include $(BACKOFF_TEST_OBJS:.o=.dep)
+endif
+endif
+
+
 BDP_ESTIMATOR_TEST_SRC = \
     test/core/transport/bdp_estimator_test.cc \
 
diff --git a/build.yaml b/build.yaml
index 4f6194e..7165216 100644
--- a/build.yaml
+++ b/build.yaml
@@ -1761,17 +1761,6 @@
   - gpr_test_util
   - gpr
   uses_polling: false
-- name: backoff_test
-  build: test
-  language: c
-  src:
-  - test/core/backoff/backoff_test.cc
-  deps:
-  - grpc_test_util
-  - grpc
-  - gpr_test_util
-  - gpr
-  uses_polling: false
 - name: bad_server_response_test
   build: test
   language: c
@@ -3481,6 +3470,17 @@
   - gpr_test_util
   - gpr
   uses_polling: false
+- name: backoff_test
+  build: test
+  language: c++
+  src:
+  - test/core/backoff/backoff_test.cc
+  deps:
+  - grpc_test_util
+  - grpc
+  - gpr_test_util
+  - gpr
+  uses_polling: false
 - name: bdp_estimator_test
   build: test
   language: c++
diff --git a/tools/run_tests/generated/sources_and_headers.json b/tools/run_tests/generated/sources_and_headers.json
index 5a3429c..8e0c226 100644
--- a/tools/run_tests/generated/sources_and_headers.json
+++ b/tools/run_tests/generated/sources_and_headers.json
@@ -104,23 +104,6 @@
       "gpr", 
       "gpr_test_util", 
       "grpc", 
-      "grpc_test_util"
-    ], 
-    "headers": [], 
-    "is_filegroup": false, 
-    "language": "c", 
-    "name": "backoff_test", 
-    "src": [
-      "test/core/backoff/backoff_test.cc"
-    ], 
-    "third_party": false, 
-    "type": "target"
-  }, 
-  {
-    "deps": [
-      "gpr", 
-      "gpr_test_util", 
-      "grpc", 
       "grpc_test_util", 
       "test_tcp_server"
     ], 
@@ -2556,6 +2539,23 @@
       "gpr", 
       "gpr_test_util", 
       "grpc", 
+      "grpc_test_util"
+    ], 
+    "headers": [], 
+    "is_filegroup": false, 
+    "language": "c++", 
+    "name": "backoff_test", 
+    "src": [
+      "test/core/backoff/backoff_test.cc"
+    ], 
+    "third_party": false, 
+    "type": "target"
+  }, 
+  {
+    "deps": [
+      "gpr", 
+      "gpr_test_util", 
+      "grpc", 
       "grpc++", 
       "grpc++_test_util", 
       "grpc_test_util"
diff --git a/tools/run_tests/generated/tests.json b/tools/run_tests/generated/tests.json
index dfd7bfa..9db1c35 100644
--- a/tools/run_tests/generated/tests.json
+++ b/tools/run_tests/generated/tests.json
@@ -132,30 +132,6 @@
     ], 
     "cpu_cost": 1.0, 
     "exclude_configs": [], 
-    "exclude_iomgrs": [], 
-    "flaky": false, 
-    "gtest": false, 
-    "language": "c", 
-    "name": "backoff_test", 
-    "platforms": [
-      "linux", 
-      "mac", 
-      "posix", 
-      "windows"
-    ], 
-    "uses_polling": false
-  }, 
-  {
-    "args": [], 
-    "benchmark": false, 
-    "ci_platforms": [
-      "linux", 
-      "mac", 
-      "posix", 
-      "windows"
-    ], 
-    "cpu_cost": 1.0, 
-    "exclude_configs": [], 
     "exclude_iomgrs": [
       "uv"
     ], 
@@ -2998,6 +2974,30 @@
     "flaky": false, 
     "gtest": false, 
     "language": "c++", 
+    "name": "backoff_test", 
+    "platforms": [
+      "linux", 
+      "mac", 
+      "posix", 
+      "windows"
+    ], 
+    "uses_polling": false
+  }, 
+  {
+    "args": [], 
+    "benchmark": false, 
+    "ci_platforms": [
+      "linux", 
+      "mac", 
+      "posix", 
+      "windows"
+    ], 
+    "cpu_cost": 1.0, 
+    "exclude_configs": [], 
+    "exclude_iomgrs": [], 
+    "flaky": false, 
+    "gtest": false, 
+    "language": "c++", 
     "name": "bdp_estimator_test", 
     "platforms": [
       "linux",