[Tracing] Minor bugs fix.

src/libplatform/tracing/trace-writer.cc

 // Copyright 2016 the V8 project 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 "src/libplatform/tracing/trace-writer.h"
 
 #include <cmath>
 
 #include "base/trace_event/common/trace_event_common.h"
 #include "src/base/platform/platform.h"
 
 namespace v8 {
 namespace platform {
 namespace tracing {
 
 // Currently we do not support JSON-escaping strings in trace arguments.
 // Thus we perform an IsJSONString() check before writing any string argument.
-// In particular, this means strings cannot have control characters or " or \.
+// In particular, this means strings cannot have control characters or \.
 V8_INLINE static bool IsJSONString(const char* str) {
   size_t len = strlen(str);
   for (size_t i = 0; i < len; ++i) {
-    if (iscntrl(str[i]) || str[i] == '\"' || str[i] == '\\') {
+    if (iscntrl(str[i]) || str[i] == '\\') {
       return false;
     }
   }
   return true;
 }
 
 void JSONTraceWriter::AppendArgValue(uint8_t type,
                                      TraceObject::ArgValue value) {
   switch (type) {
     case TRACE_VALUE_TYPE_BOOL:
@@ skipping 34 matching lines @@
     }
     case TRACE_VALUE_TYPE_POINTER:
       // JSON only supports double and int numbers.
       // So as not to lose bits from a 64-bit pointer, output as a hex string.
       stream_ << "\"" << value.as_pointer << "\"";
       break;
     case TRACE_VALUE_TYPE_STRING:
     case TRACE_VALUE_TYPE_COPY_STRING:
       // Strings are currently not JSON-escaped, so we need to perform a check
       // to see if they are valid JSON strings.
-      CHECK(value.as_string == nullptr || IsJSONString(value.as_string));
-      stream_ << "\"" << (value.as_string ? value.as_string : "NULL") << "\"";
+      CHECK(value.as_string != nullptr && IsJSONString(value.as_string));
+      stream_ << (value.as_string ? value.as_string : "NULL");
       break;
     default:
       UNREACHABLE();
       break;
   }
 }
 
 JSONTraceWriter::JSONTraceWriter(std::ostream& stream) : stream_(stream) {
   stream_ << "{\"traceEvents\":[";
 }
@@ skipping 36 matching lines @@
 
 void JSONTraceWriter::Flush() {}
 
 TraceWriter* TraceWriter::CreateJSONTraceWriter(std::ostream& stream) {
   return new JSONTraceWriter(stream);
 }
 
 }  // namespace tracing
 }  // namespace platform
 }  // namespace v8