IPC::ChannelMojo: Don't supress MOJO_RESULT_FAILED_PRECONDITION

ipc/mojo/ipc_channel_mojo_unittest.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ipc/mojo/ipc_channel_mojo.h"
 
 #include "base/base_paths.h"
 #include "base/files/file.h"
 #include "base/message_loop/message_loop.h"
 #include "base/path_service.h"
 #include "base/pickle.h"
 #include "base/threading/thread.h"
 #include "ipc/ipc_message.h"
 #include "ipc/ipc_test_base.h"
 #include "ipc/ipc_test_channel_listener.h"
 
 #if defined(OS_POSIX)
 #include "base/file_descriptor_posix.h"
 #endif
 
 namespace {
 
 class ListenerThatExpectsOK : public IPC::Listener {
  public:
-  ListenerThatExpectsOK() {}
+  ListenerThatExpectsOK()
+      : received_ok_(false) {}
 
   virtual ~ListenerThatExpectsOK() {}
 
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE {
     PickleIterator iter(message);
     std::string should_be_ok;
     EXPECT_TRUE(iter.ReadString(&should_be_ok));
     EXPECT_EQ(should_be_ok, "OK");
+    received_ok_ = true;
     base::MessageLoop::current()->Quit();
     return true;
   }
 
   virtual void OnChannelError() OVERRIDE {
-    NOTREACHED();
+    // The connection should be healthy while the listener is waiting
+    // message.  An error can occur after that because the peer
+    // process dies.
+    DCHECK(received_ok_);
   }
 
   static void SendOK(IPC::Sender* sender) {
     IPC::Message* message = new IPC::Message(
         0, 2, IPC::Message::PRIORITY_NORMAL);
     message->WriteString(std::string("OK"));
     ASSERT_TRUE(sender->Send(message));
   }
+
+ private:
+  bool received_ok_;
 };
 
 class ListenerThatShouldBeNeverCalled : public IPC::Listener {
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE {
     NOTREACHED();
     return true;
   }
 
   virtual void OnChannelError() OVERRIDE {
     NOTREACHED();
@@ skipping 193 matching lines @@
   client.Connect();
   listener.set_sender(client.channel());
 
   base::MessageLoop::current()->Run();
 
   return 0;
 }
 #endif
 
 }  // namespace