Revert 254541 "Mojo: add scaffolding for request/response support"

Reverting as broke mojo_public_bindings_unittests and
mojo_service_manager_unittests 

> Mojo: add scaffolding for request/response support
> 
> Introduces MessageHeaderWithRequestID, which extends MessageHeader, and a corresponding MessageWithRequestIDBuilder.
> 
> Adds an AcceptWithResponder method to MessageReceiver. The idea is that this will be used by generated proxy code to kick off a request that expects a response. Somehow we will bind a user supplied callback to a MessageReceiver::Accept implementation. Details TBD.
> 
> Internally, Connector might get broken down into two layers: a core pump layer (the code that currently exists) and a router layer that'll be responsible for routing incoming messages to the proper MessageReceiver, either a registered responder or the default incoming receiver.
> 
> R=davemoore@chromium.org
> 
> Review URL: https://codereview.chromium.org/185803002

TBR=darin@chromium.org

Review URL: https://codereview.chromium.org/177853004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254769 0039d316-1c4b-4281-b951-d872f2087c98

16 files changed, 68 insertions, 197 deletions

diff --git a/mojo/mojo_public.gypi b/mojo/mojo_public.gypi
index 8a88155..b4ad543 100644
--- a/mojo/mojo_public.gypi
+++ b/mojo/mojo_public.gypi
@@ -222,7 +222,6 @@
         'public/bindings/lib/message.cc',
         'public/bindings/lib/message_builder.cc',
         'public/bindings/lib/message_builder.h',
-        'public/bindings/lib/message_internal.h',
         'public/bindings/lib/message_queue.cc',
         'public/bindings/lib/message_queue.h',
         'public/bindings/lib/scratch_buffer.cc',
diff --git a/mojo/public/bindings/generators/cpp_templates/interface_definition.tmpl b/mojo/public/bindings/generators/cpp_templates/interface_definition.tmpl
index 960171c..6add826 100644
--- a/mojo/public/bindings/generators/cpp_templates/interface_definition.tmpl
+++ b/mojo/public/bindings/generators/cpp_templates/interface_definition.tmpl
@@ -49,7 +49,7 @@ void {{proxy_name}}::{{method.name}}({{params_list(method)}}) {
   mojo::Message message;
   params->EncodePointersAndHandles(message.mutable_handles());
 
-  builder.Finish(&message);
+  message.AdoptData(builder.Finish());
 
   receiver_->Accept(&message);
 }
@@ -76,12 +76,12 @@ params->{{param.name}}()
 {%- endmacro %}
 
 bool {{class_name}}Stub::Accept(mojo::Message* message) {
-  switch (message->header()->name) {
+  switch (message->data()->header.name) {
 {%- for method in interface.methods %}
     case internal::k{{class_name}}_{{method.name}}_Name: {
       internal::{{class_name}}_{{method.name}}_Params_Data* params =
           reinterpret_cast<internal::{{class_name}}_{{method.name}}_Params_Data*>(
-              message->mutable_payload());
+              message->mutable_data()->payload);
 
       if (!params->DecodePointersAndHandles(message))
         return false;
@@ -93,9 +93,3 @@ bool {{class_name}}Stub::Accept(mojo::Message* message) {
   }
   return true;
 }
-
-bool {{class_name}}Stub::AcceptWithResponder(mojo::Message* message,
-                                             mojo::MessageReceiver* responder) {
-  // TODO(darin): Implement this!
-  return false;
-}
diff --git a/mojo/public/bindings/generators/cpp_templates/interface_stub_declaration.tmpl b/mojo/public/bindings/generators/cpp_templates/interface_stub_declaration.tmpl
index e5da257..a01c5f4 100644
--- a/mojo/public/bindings/generators/cpp_templates/interface_stub_declaration.tmpl
+++ b/mojo/public/bindings/generators/cpp_templates/interface_stub_declaration.tmpl
@@ -3,9 +3,6 @@ class {{interface.name}}Stub : public mojo::MessageReceiver {
   explicit {{interface.name}}Stub({{interface.name}}* sink);
   
   virtual bool Accept(mojo::Message* message) MOJO_OVERRIDE;
-  virtual bool AcceptWithResponder(mojo::Message* message,
-                                   mojo::MessageReceiver* responder)
-                                       MOJO_OVERRIDE;
 
  private:
   {{interface.name}}* sink_;
diff --git a/mojo/public/bindings/interface.h b/mojo/public/bindings/interface.h
index 36d4bab..a472b07 100644
--- a/mojo/public/bindings/interface.h
+++ b/mojo/public/bindings/interface.h
@@ -22,8 +22,6 @@ class NoInterfaceStub : public MessageReceiver {
  public:
   NoInterfaceStub(NoInterface* unused) {}
   virtual bool Accept(Message* message) MOJO_OVERRIDE;
-  virtual bool AcceptWithResponder(Message* message, MessageReceiver* responder)
-      MOJO_OVERRIDE;
 };
 
 class NoInterface {
diff --git a/mojo/public/bindings/lib/bindings_serialization.cc b/mojo/public/bindings/lib/bindings_serialization.cc
index 31603a4..f0b14d6 100644
--- a/mojo/public/bindings/lib/bindings_serialization.cc
+++ b/mojo/public/bindings/lib/bindings_serialization.cc
@@ -40,8 +40,8 @@ bool ValidatePointer(const void* ptr, const Message& message) {
   if (reinterpret_cast<ptrdiff_t>(data) % 8 != 0)
     return false;
 
-  const uint8_t* data_start = message.data();
-  const uint8_t* data_end = data_start + message.data_num_bytes();
+  const uint8_t* data_start = reinterpret_cast<const uint8_t*>(message.data());
+  const uint8_t* data_end = data_start + message.data()->header.num_bytes;
 
   return data >= data_start && data < data_end;
 }
diff --git a/mojo/public/bindings/lib/connector.cc b/mojo/public/bindings/lib/connector.cc
index 076e30b..e2709fd 100644
--- a/mojo/public/bindings/lib/connector.cc
+++ b/mojo/public/bindings/lib/connector.cc
@@ -4,7 +4,6 @@
 
 #include "mojo/public/bindings/lib/connector.h"
 
-#include <assert.h>
 #include <stdlib.h>
 
 #include "mojo/public/bindings/error_handler.h"
@@ -43,7 +42,7 @@ bool Connector::Accept(Message* message) {
   MojoResult rv = WriteMessageRaw(
       message_pipe_.get(),
       message->data(),
-      message->data_num_bytes(),
+      message->data()->header.num_bytes,
       message->mutable_handles()->empty() ? NULL :
           reinterpret_cast<const MojoHandle*>(
               &message->mutable_handles()->front()),
@@ -71,13 +70,6 @@ bool Connector::Accept(Message* message) {
   return true;
 }
 
-bool Connector::AcceptWithResponder(Message* message,
-                                    MessageReceiver* responder) {
-  // TODO(darin): Implement this!
-  assert(false);
-  return false;
-}
-
 // static
 void Connector::CallOnHandleReady(void* closure, MojoResult result) {
   Connector* self = static_cast<Connector*>(closure);
@@ -127,7 +119,7 @@ void Connector::ReadMore() {
     }
 
     Message message;
-    message.AllocUninitializedData(num_bytes);
+    message.AllocData(num_bytes);
     message.mutable_handles()->resize(num_handles);
 
     rv = ReadMessageRaw(
diff --git a/mojo/public/bindings/lib/connector.h b/mojo/public/bindings/lib/connector.h
index c0d9802..09bc4b5 100644
--- a/mojo/public/bindings/lib/connector.h
+++ b/mojo/public/bindings/lib/connector.h
@@ -48,8 +48,6 @@ class Connector : public MessageReceiver {
 
   // MessageReceiver implementation:
   virtual bool Accept(Message* message) MOJO_OVERRIDE;
-  virtual bool AcceptWithResponder(Message* message, MessageReceiver* responder)
-      MOJO_OVERRIDE;
 
  private:
   static void CallOnHandleReady(void* closure, MojoResult result);
diff --git a/mojo/public/bindings/lib/interface.cc b/mojo/public/bindings/lib/interface.cc
index cb7b11d..a7cf3ff 100644
--- a/mojo/public/bindings/lib/interface.cc
+++ b/mojo/public/bindings/lib/interface.cc
@@ -10,10 +10,5 @@ bool NoInterfaceStub::Accept(Message* message) {
   return false;
 }
 
-bool NoInterfaceStub::AcceptWithResponder(Message* message,
-                                          MessageReceiver* responder) {
-  return false;
-}
-
 }  // namespace mojo
 
diff --git a/mojo/public/bindings/lib/message.cc b/mojo/public/bindings/lib/message.cc
index f33f250a..56561b3 100644
--- a/mojo/public/bindings/lib/message.cc
+++ b/mojo/public/bindings/lib/message.cc
@@ -12,8 +12,7 @@
 namespace mojo {
 
 Message::Message()
-    : data_num_bytes_(0),
-      data_(NULL) {
+    : data_(NULL) {
 }
 
 Message::~Message() {
@@ -26,20 +25,17 @@ Message::~Message() {
   }
 }
 
-void Message::AllocUninitializedData(uint32_t num_bytes) {
+void Message::AllocData(uint32_t num_bytes) {
   assert(!data_);
-  data_num_bytes_ = num_bytes;
-  data_ = static_cast<internal::MessageData*>(malloc(num_bytes));
+  data_ = static_cast<MessageData*>(malloc(num_bytes));
 }
 
-void Message::AdoptData(uint32_t num_bytes, internal::MessageData* data) {
+void Message::AdoptData(MessageData* data) {
   assert(!data_);
-  data_num_bytes_ = num_bytes;
   data_ = data;
 }
 
 void Message::Swap(Message* other) {
-  std::swap(data_num_bytes_, other->data_num_bytes_);
   std::swap(data_, other->data_);
   std::swap(handles_, other->handles_);
 }
diff --git a/mojo/public/bindings/lib/message_builder.cc b/mojo/public/bindings/lib/message_builder.cc
index 5cbe037..a553e68 100644
--- a/mojo/public/bindings/lib/message_builder.cc
+++ b/mojo/public/bindings/lib/message_builder.cc
@@ -9,43 +9,19 @@
 namespace mojo {
 namespace internal {
 
-template <typename Header>
-void Allocate(Buffer* buf, Header** header) {
-  *header = static_cast<Header*>(buf->Allocate(sizeof(Header)));
-  (*header)->num_bytes = sizeof(Header);
-}
-
-MessageBuilder::MessageBuilder(uint32_t name, size_t payload_size)
+MessageBuilder::MessageBuilder(uint32_t message_name, size_t payload_size)
     : buf_(sizeof(MessageHeader) + payload_size) {
-  MessageHeader* header;
-  Allocate(&buf_, &header);
-  header->num_fields = 2;
-  header->name = name;
+  MessageHeader* header =
+      static_cast<MessageHeader*>(buf_.Allocate(sizeof(MessageHeader)));
+  header->num_bytes = static_cast<uint32_t>(buf_.size());
+  header->name = message_name;
 }
 
 MessageBuilder::~MessageBuilder() {
 }
 
-void MessageBuilder::Finish(Message* message) {
-  message->AdoptData(static_cast<uint32_t>(buf_.size()),
-                     static_cast<MessageData*>(buf_.Leak()));
-}
-
-MessageBuilder::MessageBuilder(size_t size)
-    : buf_(size) {
-}
-
-MessageWithRequestIDBuilder::MessageWithRequestIDBuilder(uint32_t name,
-                                                         size_t payload_size,
-                                                         uint32_t flags,
-                                                         uint64_t request_id)
-    : MessageBuilder(sizeof(MessageHeaderWithRequestID) + payload_size) {
-  MessageHeaderWithRequestID* header;
-  Allocate(&buf_, &header);
-  header->num_fields = 3;
-  header->name = name;
-  header->flags = flags;
-  header->request_id = request_id;
+MessageData* MessageBuilder::Finish() {
+  return static_cast<MessageData*>(buf_.Leak());
 }
 
 }  // namespace internal
diff --git a/mojo/public/bindings/lib/message_builder.h b/mojo/public/bindings/lib/message_builder.h
index a8a0240..a8dfdfa 100644
--- a/mojo/public/bindings/lib/message_builder.h
+++ b/mojo/public/bindings/lib/message_builder.h
@@ -10,13 +10,14 @@
 #include "mojo/public/bindings/lib/fixed_buffer.h"
 
 namespace mojo {
-class Message;
+struct MessageData;
 
 namespace internal {
 
+// Used to construct a MessageData object.
 class MessageBuilder {
  public:
-  MessageBuilder(uint32_t name, size_t payload_size);
+  MessageBuilder(uint32_t message_name, size_t payload_size);
   ~MessageBuilder();
 
   Buffer* buffer() { return &buf_; }
@@ -24,21 +25,14 @@ class MessageBuilder {
   // Call Finish when done making allocations in |buffer()|. A heap-allocated
   // MessageData object will be returned. When no longer needed, use |free()|
   // to release the MessageData object's memory.
-  void Finish(Message* message);
+  MessageData* Finish();
 
- protected:
-  explicit MessageBuilder(size_t size);
+ private:
   FixedBuffer buf_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(MessageBuilder);
 };
 
-class MessageWithRequestIDBuilder : public MessageBuilder {
- public:
-  MessageWithRequestIDBuilder(uint32_t name, size_t payload_size,
-                              uint32_t flags, uint64_t request_id);
-};
-
 }  // namespace internal
 }  // namespace mojo
 
diff --git a/mojo/public/bindings/lib/message_internal.h b/mojo/public/bindings/lib/message_internal.h
deleted file mode 100644
index d3f8338..0000000
--- a/mojo/public/bindings/lib/message_internal.h
+++ /dev/null
@@ -1,50 +0,0 @@
-// 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.
-
-#ifndef MOJO_PUBLIC_BINDINGS_LIB_MESSAGE_INTERNAL_H_
-#define MOJO_PUBLIC_BINDINGS_LIB_MESSAGE_INTERNAL_H_
-
-#include "mojo/public/bindings/lib/bindings_internal.h"
-
-namespace mojo {
-namespace internal {
-
-#pragma pack(push, 1)
-
-enum {
-  kMessageExpectsResponse = 1 << 0,
-  kMessageIsResponse      = 1 << 1
-};
-
-struct MessageHeader : internal::StructHeader {
-  uint32_t name;
-  uint32_t flags;
-};
-MOJO_COMPILE_ASSERT(sizeof(MessageHeader) == 16, bad_sizeof_MessageHeader);
-
-struct MessageHeaderWithRequestID : MessageHeader {
-  uint64_t request_id;
-};
-MOJO_COMPILE_ASSERT(sizeof(MessageHeaderWithRequestID) == 24,
-                    bad_sizeof_MessageHeaderWithRequestID);
-
-struct MessageData {
-  MessageHeader header;
-  uint8_t payload[1];
-};
-MOJO_COMPILE_ASSERT(sizeof(MessageData) == 17, bad_sizeof_MessageData);
-
-struct MessageDataWithRequestID {
-  MessageHeaderWithRequestID header;
-  uint8_t payload[1];
-};
-MOJO_COMPILE_ASSERT(sizeof(MessageDataWithRequestID) == 25,
-                    bad_sizeof_MessageDataWithRequestID);
-
-#pragma pack(pop)
-
-}  // namespace internal
-}  // namespace mojo
-
-#endif  // MOJO_PUBLIC_BINDINGS_LIB_MESSAGE_INTERNAL_H_
diff --git a/mojo/public/bindings/lib/sync_dispatcher.cc b/mojo/public/bindings/lib/sync_dispatcher.cc
index f27fc17..eee0be4 100644
--- a/mojo/public/bindings/lib/sync_dispatcher.cc
+++ b/mojo/public/bindings/lib/sync_dispatcher.cc
@@ -30,7 +30,7 @@ bool WaitForMessageAndDispatch(MessagePipeHandle handle,
   }
 
   Message message;
-  message.AllocUninitializedData(num_bytes);
+  message.AllocData(num_bytes);
   message.mutable_handles()->resize(num_handles);
 
   MojoResult rv = ReadMessageRaw(
diff --git a/mojo/public/bindings/message.h b/mojo/public/bindings/message.h
index 7b058b8..fa13515 100644
--- a/mojo/public/bindings/message.h
+++ b/mojo/public/bindings/message.h
@@ -5,60 +5,52 @@
 #ifndef MOJO_PUBLIC_BINDINGS_MESSAGE_H_
 #define MOJO_PUBLIC_BINDINGS_MESSAGE_H_
 
-#include <assert.h>
-
 #include <vector>
 
-#include "mojo/public/bindings/lib/message_internal.h"
+#include "mojo/public/system/core_cpp.h"
 
 namespace mojo {
 
+#pragma pack(push, 1)
+
+struct MessageHeader {
+  //uint32_t deprecated_num_bytes;
+  uint32_t num_bytes;
+  uint32_t name;
+};
+MOJO_COMPILE_ASSERT(sizeof(MessageHeader) == 8, bad_sizeof_MessageHeader);
+
+struct MessageData {
+  MessageHeader header;
+  uint8_t payload[1];
+};
+MOJO_COMPILE_ASSERT(sizeof(MessageData) == 9, bad_sizeof_MessageData);
+
+#pragma pack(pop)
+
 // Message is a holder for the data and handles to be sent over a MessagePipe.
 // Message owns its data and handles, but a consumer of Message is free to
-// mutate the data and handles members. The message's data is comprised of a
-// header followed by payload.
+// manipulate the data and handles members.
 class Message {
  public:
   Message();
   ~Message();
 
-  // These may only be called on a newly created Message object.
-  void AllocUninitializedData(uint32_t num_bytes);
-  void AdoptData(uint32_t num_bytes, internal::MessageData* data);
+  // These may only be called on a newly initialized Message object.
+  void AllocData(uint32_t num_bytes);  // |data()| is uninitialized.
+  void AdoptData(MessageData* data);
 
   // Swaps data and handles between this Message and another.
   void Swap(Message* other);
 
-  uint32_t data_num_bytes() const { return data_num_bytes_; }
-
-  // Access the raw bytes of the message.
-  const uint8_t* data() const { return
-    reinterpret_cast<const uint8_t*>(data_);
-  }
-  uint8_t* mutable_data() { return reinterpret_cast<uint8_t*>(data_); }
-
-  // Access the header.
-  const internal::MessageHeader* header() const { return &data_->header; }
+  const MessageData* data() const { return data_; }
+  MessageData* mutable_data() { return data_; }
 
-  // Access the request_id field (if present).
-  bool has_request_id() const { return data_->header.num_fields == 3; }
-  uint64_t request_id() const {
-    assert(has_request_id());
-    return static_cast<internal::MessageHeaderWithRequestID*>(&data_->header)->
-        request_id;
-  }
-
-  // Access the payload.
-  const uint8_t* payload() const { return data_->payload; }
-  uint8_t* mutable_payload() { return data_->payload; }
-
-  // Access the handles.
   const std::vector<Handle>* handles() const { return &handles_; }
   std::vector<Handle>* mutable_handles() { return &handles_; }
 
  private:
-  uint32_t data_num_bytes_;
-  internal::MessageData* data_;  // Heap-allocated using malloc.
+  MessageData* data_;  // Heap-allocated using malloc.
   std::vector<Handle> handles_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(Message);
@@ -66,17 +58,11 @@ class Message {
 
 class MessageReceiver {
  public:
-  // The receiver may mutate the given message.  Returns true if the message
+  // The receiver may mutate the given message or take ownership of its
+  // |message->data| member by setting it to NULL.  Returns true if the message
   // was accepted and false otherwise, indicating that the message was invalid
   // or malformed.
   virtual bool Accept(Message* message) = 0;
-
-  // A variant on Accept that registers a receiver to handle the response
-  // message generated from the given message. The responder's Accept method
-  // will be called some time after AcceptWithResponder returns. The responder
-  // will be unregistered once its Accept method has been called.
-  virtual bool AcceptWithResponder(Message* message,
-                                   MessageReceiver* responder) = 0;
 };
 
 }  // namespace mojo
diff --git a/mojo/public/bindings/tests/connector_unittest.cc b/mojo/public/bindings/tests/connector_unittest.cc
index b0f9cf1..8ff7de5 100644
--- a/mojo/public/bindings/tests/connector_unittest.cc
+++ b/mojo/public/bindings/tests/connector_unittest.cc
@@ -6,7 +6,6 @@
 #include <string.h>
 
 #include "mojo/public/bindings/lib/connector.h"
-#include "mojo/public/bindings/lib/message_builder.h"
 #include "mojo/public/bindings/lib/message_queue.h"
 #include "mojo/public/environment/environment.h"
 #include "mojo/public/system/macros.h"
@@ -26,11 +25,6 @@ class MessageAccumulator : public MessageReceiver {
     return true;
   }
 
-  virtual bool AcceptWithResponder(Message* message, MessageReceiver* responder)
-      MOJO_OVERRIDE {
-    return false;
-  }
-
   bool IsEmpty() const {
     return queue_.IsEmpty();
   }
@@ -57,9 +51,12 @@ class ConnectorTest : public testing::Test {
 
   void AllocMessage(const char* text, Message* message) {
     size_t payload_size = strlen(text) + 1;  // Plus null terminator.
-    internal::MessageBuilder builder(1, payload_size);
-    memcpy(builder.buffer()->Allocate(payload_size), text, payload_size);
-    builder.Finish(message);
+    size_t num_bytes = sizeof(MessageHeader) + payload_size;
+    message->AllocData(static_cast<uint32_t>(num_bytes));
+    message->mutable_data()->header.num_bytes =
+        static_cast<uint32_t>(num_bytes);
+    message->mutable_data()->header.name = 1;
+    memcpy(message->mutable_data()->payload, text, payload_size);
   }
 
   void PumpMessages() {
@@ -98,7 +95,8 @@ TEST_F(ConnectorTest, Basic) {
 
   EXPECT_EQ(
       std::string(kText),
-      std::string(reinterpret_cast<const char*>(message_received.payload())));
+      std::string(
+          reinterpret_cast<const char*>(message_received.data()->payload)));
 }
 
 TEST_F(ConnectorTest, Basic_EarlyIncomingReceiver) {
@@ -124,7 +122,8 @@ TEST_F(ConnectorTest, Basic_EarlyIncomingReceiver) {
 
   EXPECT_EQ(
       std::string(kText),
-      std::string(reinterpret_cast<const char*>(message_received.payload())));
+      std::string(
+          reinterpret_cast<const char*>(message_received.data()->payload)));
 }
 
 TEST_F(ConnectorTest, Basic_TwoMessages) {
@@ -153,7 +152,8 @@ TEST_F(ConnectorTest, Basic_TwoMessages) {
 
     EXPECT_EQ(
         std::string(kText[i]),
-        std::string(reinterpret_cast<const char*>(message_received.payload())));
+        std::string(
+            reinterpret_cast<const char*>(message_received.data()->payload)));
   }
 }
 
@@ -215,7 +215,8 @@ TEST_F(ConnectorTest, MessageWithHandles) {
 
   EXPECT_EQ(
       std::string(kText),
-      std::string(reinterpret_cast<const char*>(message_received.payload())));
+      std::string(
+          reinterpret_cast<const char*>(message_received.data()->payload)));
   ASSERT_EQ(1U, message_received.handles()->size());
 
   // Now send a message to the transferred handle and confirm it's sent through
@@ -242,7 +243,8 @@ TEST_F(ConnectorTest, MessageWithHandles) {
 
   EXPECT_EQ(
       std::string(kText),
-      std::string(reinterpret_cast<const char*>(message_received.payload())));
+      std::string(
+          reinterpret_cast<const char*>(message_received.data()->payload)));
 }
 
 }  // namespace test
diff --git a/mojo/public/bindings/tests/sample_service_unittest.cc b/mojo/public/bindings/tests/sample_service_unittest.cc
index 390c78b..b7d8f6c 100644
--- a/mojo/public/bindings/tests/sample_service_unittest.cc
+++ b/mojo/public/bindings/tests/sample_service_unittest.cc
@@ -271,7 +271,7 @@ class SimpleMessageReceiver : public mojo::MessageReceiver {
 
     if (g_dump_message_as_hex) {
       DumpHex(reinterpret_cast<const uint8_t*>(message->data()),
-              message->data_num_bytes());
+              message->data()->header.num_bytes);
     }
 
     // In the receiving process, an implementation of ServiceStub is known to
@@ -281,12 +281,6 @@ class SimpleMessageReceiver : public mojo::MessageReceiver {
     ServiceStub stub(&impl);
     return stub.Accept(message);
   }
-
-  virtual bool AcceptWithResponder(mojo::Message* message,
-                                   mojo::MessageReceiver* responder)
-                                       MOJO_OVERRIDE {
-    return false;
-  }
 };
 
 }  // namespace