ChannelMojo Refactoring: Merge MessageReader into MessagePipeReader

MessageReader was the sole subclass  of MessageReader.
There is no need to have two classes.
This CL also decouple ChannelMojo from MessagePipeReader
through a delegate interface.

R=viettrungluu@chromium.org
BUG=377980

Review URL: https://codereview.chromium.org/750673002

Cr-Commit-Position: refs/heads/master@{#305728}

ipc/mojo/BUILD.gn

@@ -17,8 +17,6 @@ component("mojo") {
     "ipc_channel_mojo.h",
     "ipc_channel_mojo_host.cc",
     "ipc_channel_mojo_host.h",
-    "ipc_channel_mojo_readers.cc",
-    "ipc_channel_mojo_readers.h",
     "ipc_mojo_bootstrap.cc",
     "ipc_mojo_bootstrap.h",
     "ipc_message_pipe_reader.cc",

ipc/mojo/ipc_channel_mojo.cc

@@ -9,7 +9,6 @@
 #include "base/lazy_instance.h"
 #include "ipc/ipc_listener.h"
 #include "ipc/mojo/client_channel.mojom.h"
-#include "ipc/mojo/ipc_channel_mojo_readers.h"
 #include "ipc/mojo/ipc_mojo_bootstrap.h"
 #include "mojo/edk/embedder/embedder.h"
 #include "mojo/public/cpp/bindings/error_handler.h"
@@ -279,7 +278,7 @@ void ChannelMojo::OnBootstrapError() {
 void ChannelMojo::InitMessageReader(mojo::ScopedMessagePipeHandle pipe,
                                     int32_t peer_pid) {
   message_reader_ =
-      make_scoped_ptr(new internal::MessageReader(pipe.Pass(), this));
+      make_scoped_ptr(new internal::MessagePipeReader(pipe.Pass(), this));
 
   for (size_t i = 0; i < pending_messages_.size(); ++i) {
     bool sent = message_reader_->Send(make_scoped_ptr(pending_messages_[i]));

ipc/mojo/ipc_channel_mojo.h

@@ -20,13 +20,6 @@
 
 namespace IPC {
 
-namespace internal {
-class ControlReader;
-class ServerControlReader;
-class ClientControlReader;
-class MessageReader;
-}
-
 // Mojo-based IPC::Channel implementation over a platform handle.
 //
 // ChannelMojo builds Mojo MessagePipe using underlying pipe given by
@@ -51,8 +44,10 @@ class MessageReader;
 // TODO(morrita): Add APIs to create extra MessagePipes to let
 //                Mojo-based objects talk over this Channel.
 //
-class IPC_MOJO_EXPORT ChannelMojo : public Channel,
-                                    public MojoBootstrap::Delegate {
+class IPC_MOJO_EXPORT ChannelMojo
+    : public Channel,
+      public MojoBootstrap::Delegate,
+      public NON_EXPORTED_BASE(internal::MessagePipeReader::Delegate) {
  public:
   class Delegate {
    public:
@@ -111,10 +106,10 @@ class IPC_MOJO_EXPORT ChannelMojo : public Channel,
   // MojoBootstrapDelegate implementation
   void OnBootstrapError() override;
 
-  // Called from MessagePipeReader implementations
-  void OnMessageReceived(Message& message);
-  void OnPipeClosed(internal::MessagePipeReader* reader);
-  void OnPipeError(internal::MessagePipeReader* reader);
+  // MessagePipeReader::Delegate
+  void OnMessageReceived(Message& message) override;
+  void OnPipeClosed(internal::MessagePipeReader* reader) override;
+  void OnPipeError(internal::MessagePipeReader* reader) override;
 
  protected:
   ChannelMojo(Delegate* delegate,
@@ -149,7 +144,7 @@ class IPC_MOJO_EXPORT ChannelMojo : public Channel,
   scoped_ptr<mojo::embedder::ChannelInfo,
              ChannelInfoDeleter> channel_info_;
 
-  scoped_ptr<internal::MessageReader, ReaderDeleter> message_reader_;
+  scoped_ptr<internal::MessagePipeReader, ReaderDeleter> message_reader_;
   ScopedVector<Message> pending_messages_;
 
   base::WeakPtrFactory<ChannelMojo> weak_factory_;

ipc/mojo/ipc_channel_mojo_unittest.cc

@@ -14,7 +14,6 @@
 #include "ipc/ipc_test_base.h"
 #include "ipc/ipc_test_channel_listener.h"
 #include "ipc/mojo/ipc_channel_mojo_host.h"
-#include "ipc/mojo/ipc_channel_mojo_readers.h"
 
 #if defined(OS_POSIX)
 #include "base/file_descriptor_posix.h"