Make IPC::ParamTraits<>GetSize work with base::Value as a result of JSON parsing.

ipc/ipc_message_utils.cc

 // Copyright (c) 2012 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 "ipc/ipc_message_utils.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include "base/files/file_path.h"
@@ skipping 78 matching lines @@
       break;
     case base::Value::TYPE_INTEGER:
       sizer->AddInt();
       break;
     case base::Value::TYPE_DOUBLE:
       sizer->AddDouble();
       break;
     case base::Value::TYPE_STRING: {
       const base::StringValue* result;
       value->GetAsString(&result);
-      DCHECK(result);
-      GetParamSize(sizer, result->GetString());
+      if (value->GetAsString(&result)) {
+        DCHECK(result);
+        GetParamSize(sizer, result->GetString());
+      } else {
+        std::string str;
+        bool as_string_result = value->GetAsString(&str);
+        DCHECK(as_string_result);
+        GetParamSize(sizer, str);
+      }
       break;
     }
     case base::Value::TYPE_BINARY: {
       const base::BinaryValue* binary =
           static_cast<const base::BinaryValue*>(value);
       sizer->AddData(static_cast<int>(binary->GetSize()));
       break;
     }
     case base::Value::TYPE_DICTIONARY: {
       sizer->AddInt();
@@ skipping 1107 matching lines @@
   return result;
 }
 
 void ParamTraits<MSG>::Log(const param_type& p, std::string* l) {
   l->append("<MSG>");
 }
 
 #endif  // OS_WIN
 
 }  // namespace IPC