Remove dependency from //mojo to //crypto

mojo/dart/embedder/builtin_natives.cc

 // 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.
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include "base/files/file_enumerator.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
-#include "crypto/random.h"
+#include "base/rand_util.h"
 #include "dart/runtime/include/dart_api.h"
 #include "mojo/dart/embedder/builtin.h"
 #include "mojo/dart/embedder/mojo_natives.h"
 
 #if defined(OS_ANDROID)
 #include <android/log.h>
 #endif
 
 namespace mojo {
 namespace dart {
@@ skipping 291 matching lines @@
   if (!GetInt64Value(count_obj, &count64) || (count64 < 0) ||
       (count64 > kMaxRandomBytes)) {
     Dart_Handle error = Dart_NewStringFromCString(
         "Invalid argument: count must be a positive int "
         "less than or equal to 4096.");
     Dart_ThrowException(error);
   }
   intptr_t count = static_cast<intptr_t>(count64);
   scoped_ptr<uint8_t[]> buffer(new uint8_t[count]);
 
-  crypto::RandBytes(reinterpret_cast<void*>(buffer.get()), count);
+  base::RandBytes(reinterpret_cast<void*>(buffer.get()), count);
 
   Dart_Handle result = Dart_NewTypedData(Dart_TypedData_kUint8, count);
   if (Dart_IsError(result)) {
     Dart_Handle error = Dart_NewStringFromCString(
         "Failed to allocate storage.");
     Dart_ThrowException(error);
   }
   Dart_ListSetAsBytes(result, 0, buffer.get(), count);
   Dart_SetReturnValue(args, result);
 }
 
 }  // namespace bin
 }  // namespace dart