Convert mojo::system::ChannelEndpointClient to use our new refcounting stuff (instead of base's).

mojo/edk/system/test_channel_endpoint_client.cc

Index: mojo/edk/system/test_channel_endpoint_client.cc
diff --git a/mojo/edk/system/test_channel_endpoint_client.cc b/mojo/edk/system/test_channel_endpoint_client.cc
index 9f48a809a305e4b6efbb65f8f0b12eb7bdb5a0fb..957fa964c6ea45970aa200aabcb6e313dd198bd7 100644
--- a/mojo/edk/system/test_channel_endpoint_client.cc
+++ b/mojo/edk/system/test_channel_endpoint_client.cc
@@ -14,10 +14,6 @@ namespace mojo {
 namespace system {
 namespace test {
 
-TestChannelEndpointClient::TestChannelEndpointClient()
-    : port_(0), read_event_(nullptr) {
-}
-
 void TestChannelEndpointClient::Init(unsigned port,
                                      RefPtr<ChannelEndpoint>&& endpoint) {
   MutexLocker locker(&mutex_);
@@ -72,6 +68,9 @@ void TestChannelEndpointClient::OnDetachFromChannel(unsigned port) {
   endpoint_ = nullptr;
 }
 
+TestChannelEndpointClient::TestChannelEndpointClient()
+    : port_(0), read_event_(nullptr) {}
+
 TestChannelEndpointClient::~TestChannelEndpointClient() {
   EXPECT_FALSE(endpoint_);
 }