Reland #1: Clean up interface of attachment broker.

ipc/attachment_broker_privileged_win_unittest.cc

Index: ipc/attachment_broker_privileged_win_unittest.cc
diff --git a/ipc/attachment_broker_privileged_win_unittest.cc b/ipc/attachment_broker_privileged_win_unittest.cc
index 2140fd93326ee0786be338dc6770c096958b65d2..c4110bd3082301a85e660abc6d3ddf9c109d3407 100644
--- a/ipc/attachment_broker_privileged_win_unittest.cc
+++ b/ipc/attachment_broker_privileged_win_unittest.cc
@@ -161,7 +161,7 @@ class IPCAttachmentBrokerPrivilegedWinTest : public IPCTestBase {
     broker_->AddObserver(&observer_);
     set_attachment_broker(broker_.get());
     CreateChannel(&proxy_listener_);
-    broker_->set_sender(channel());
+    broker_->DesignateBrokerCommunicationChannel(channel());
     ASSERT_TRUE(ConnectChannel());
     ASSERT_TRUE(StartClient());
   }
@@ -278,6 +278,9 @@ TEST_F(IPCAttachmentBrokerPrivilegedWinTest, SendHandleToSelf) {
 
   set_broker(new MockBroker);
   CommonSetUp();
+  // Technically, the channel is an endpoint, but we need the proxy listener to
+  // receive the messages so that it can quit the message loop.
+  channel()->set_attachment_broker_endpoint(false);
   get_proxy_listener()->set_listener(get_broker());
 
   HANDLE h = CreateTempFile();