ChannelMojo: Handle errors in pending message processing.

ipc/mojo/ipc_channel_mojo_readers.h

Index: ipc/mojo/ipc_channel_mojo_readers.h
diff --git a/ipc/mojo/ipc_channel_mojo_readers.h b/ipc/mojo/ipc_channel_mojo_readers.h
index 13ddeada45dabe40fb951c6c4951c9e311d54564..54a8fbcc986124e01038ca37994184aaf3e7225e 100644
--- a/ipc/mojo/ipc_channel_mojo_readers.h
+++ b/ipc/mojo/ipc_channel_mojo_readers.h
@@ -26,7 +26,7 @@ class Message;
 namespace internal {
 
 // A MessagePipeReader implementation for IPC::Message communication.
-class MessageReader : public MessagePipeReader {
+class IPC_MOJO_EXPORT MessageReader : public MessagePipeReader {
  public:
   MessageReader(mojo::ScopedMessagePipeHandle pipe, ChannelMojo* owner);
 
@@ -38,6 +38,14 @@ class MessageReader : public MessagePipeReader {
   virtual void OnPipeError(MojoResult error) OVERRIDE;
 
  private:
+  // Be virtual for testing.
+  virtual MojoResult WriteMessageToPipe(

[yzshen1, 2014/09/15 17:26:07]

Is it possible to do it in a different way? For example, forcefully close the
handle to trigger a write error? I am a little afraid making it virtual is more
expensive than before, and this is on the performance critical path. What do you
think?

[Hajime Morrita, 2014/09/15 18:16:53]

Sounds good. I made change and things got much simpler.
Thanks for the suggestion!

+      const void* bytes,
+      uint32_t num_bytes,
+      const MojoHandle* handles,
+      uint32_t num_handles,
+      MojoWriteMessageFlags flags);
+
   ChannelMojo* owner_;
 
   DISALLOW_COPY_AND_ASSIGN(MessageReader);