C++ bindings: A struct's Deserialize() now does validation before deserializing.

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

 // 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_CPP_BINDINGS_LIB_VALIDATION_ERRORS_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_LIB_VALIDATION_ERRORS_H_
 
 #include <sstream>
 #include <string>
 
@@ skipping 45 matching lines @@
   MESSAGE_HEADER_UNKNOWN_METHOD,
   // Two parallel arrays which are supposed to represent a map have different
   // lengths.
   DIFFERENT_SIZED_ARRAYS_IN_MAP,
   // A non-nullable union is set to null. (Has size 0)
   UNEXPECTED_NULL_UNION,
 };
 
 const char* ValidationErrorToString(ValidationError error);
 
+// TODO(vardhan): This can die, along with |ValidationErrorObserverForTesting|.
 void ReportValidationError(ValidationError error,
                            std::string* description = nullptr);
 
 // Only used by validation tests and when there is only one thread doing message
 // validation.
 class ValidationErrorObserverForTesting {
  public:
   ValidationErrorObserverForTesting();
   ~ValidationErrorObserverForTesting();
 
@@ skipping 42 matching lines @@
 #define MOJO_INTERNAL_DEBUG_SET_ERROR_MSG(err_msg) \
   true ? (void)0                                   \
        : ::mojo::internal::VoidifyOstream() &      \
              ::mojo::internal::ValidationErrorStringStream(err_msg).stream()
 #else
 #define MOJO_INTERNAL_DEBUG_SET_ERROR_MSG(err_msg) \
   ::mojo::internal::ValidationErrorStringStream(err_msg).stream()
 #endif  // NDEBUG
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_VALIDATION_ERRORS_H_