Fix posix IPC channel hanging problem.

ipc/ipc_channel_posix_unittest.cc

Index: ipc/ipc_channel_posix_unittest.cc
diff --git a/ipc/ipc_channel_posix_unittest.cc b/ipc/ipc_channel_posix_unittest.cc
index 66ddeb2b49676444245ceab4e185a0dd84e926b8..4cbf9c0a22b89e061adfab43c4754cb72ddf4cfd 100644
--- a/ipc/ipc_channel_posix_unittest.cc
+++ b/ipc/ipc_channel_posix_unittest.cc
@@ -228,6 +228,28 @@ TEST_F(IPCChannelPosixTest, BasicConnected) {
   ASSERT_FALSE(channel2.AcceptsConnections());
 }
 
+// If a connection closes right before a Send() call, we may end up closing
+// the connection without notifying the listener, which can cause hangs in
+// sync_message_filter and others. Make sure the listener is notified.
+TEST_F(IPCChannelPosixTest, SendHangTest) {
+  IPCChannelPosixTestListener out_listener(true);
+  IPCChannelPosixTestListener in_listener(true);
+  IPC::ChannelHandle in_handle("IN");
+  IPC::Channel in_chan(in_handle, IPC::Channel::MODE_SERVER, &in_listener);
+  base::FileDescriptor out_fd(in_chan.TakeClientFileDescriptor(), false);
+  IPC::ChannelHandle out_handle("OUT", out_fd);
+  IPC::Channel out_chan(out_handle, IPC::Channel::MODE_CLIENT, &out_listener);
+  ASSERT_TRUE(in_chan.Connect());
+  ASSERT_TRUE(out_chan.Connect());
+  in_chan.Close();  // simulate remote process dying at an unforunate time.
+  // Send will fail, because it cannot write the message.
+  ASSERT_FALSE(out_chan.Send(new IPC::Message(
+      0,  // routing_id
+      kQuitMessage,  // message type
+      IPC::Message::PRIORITY_NORMAL)));
+  ASSERT_EQ(IPCChannelPosixTestListener::CHANNEL_ERROR, out_listener.status());
+}
+
 TEST_F(IPCChannelPosixTest, AdvancedConnected) {
   // Test creating a connection to an external process.
   IPCChannelPosixTestListener listener(false);