Mojo: Report bindings validation errors via MojoNotifyBadMessage

mojo/public/cpp/bindings/lib/pipe_control_message_handler.h

 // Copyright 2015 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_CPP_BINDINGS_LIB_PIPE_CONTROL_MESSAGE_HANDLER_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_LIB_PIPE_CONTROL_MESSAGE_HANDLER_H_
 
 #include "base/macros.h"
 #include "mojo/public/cpp/bindings/lib/interface_id.h"
 #include "mojo/public/cpp/bindings/lib/serialization_context.h"
 #include "mojo/public/cpp/bindings/message.h"
 
 namespace mojo {
 namespace internal {
 
 class PipeControlMessageHandlerDelegate;
 
 // Handler for messages defined in pipe_control_messages.mojom.
 class PipeControlMessageHandler : public MessageReceiver {
  public:
   explicit PipeControlMessageHandler(
       PipeControlMessageHandlerDelegate* delegate);
   ~PipeControlMessageHandler() override;
 
+  // Sets the description for this handler. Used only when reporting validation
+  // errors.
+  void SetDescription(const std::string& description);
+
   // NOTE: |message| must have passed message header validation.
   static bool IsPipeControlMessage(const Message* message);
 
   // MessageReceiver implementation:
 
   // NOTE: |message| must:
   //   - have passed message header validation; and
   //   - be a pipe control message (i.e., IsPipeControlMessage() returns true).
   // If the method returns false, the message pipe should be closed.
   bool Accept(Message* message) override;
 
  private:
   // |message| must have passed message header validation.
-  bool Validate(const Message* message);
+  bool Validate(Message* message);
   bool RunOrClosePipe(Message* message);
 
+  std::string description_;
   PipeControlMessageHandlerDelegate* const delegate_;
   SerializationContext context_;
 
   DISALLOW_COPY_AND_ASSIGN(PipeControlMessageHandler);
 };
 
 }  // namespace internal
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_PIPE_CONTROL_MESSAGE_HANDLER_H_