Stop doing unnecessary UTF-8 to UTF-16 conversions in JSONWriter.

base/debug/trace_event_impl.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 "base/debug/trace_event_impl.h"
 
 #include <algorithm>
 
 #include "base/base_switches.h"
 #include "base/bind.h"
@@ skipping 644 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.
       StringAppendF(out, "\"0x%" PRIx64 "\"", static_cast<uint64>(
                                      reinterpret_cast<intptr_t>(
                                      value.as_pointer)));
       break;
     case TRACE_VALUE_TYPE_STRING:
     case TRACE_VALUE_TYPE_COPY_STRING:
-      JsonDoubleQuote(value.as_string ? value.as_string : "NULL", true, out);
+      EscapeJSONString(value.as_string ? value.as_string : "NULL", true, out);
       break;
     default:
       NOTREACHED() << "Don't know how to print this value";
       break;
   }
 }
 
 void TraceEvent::AppendAsJSON(std::string* out) const {
   int64 time_int64 = timestamp_.ToInternalValue();
   int process_id = TraceLog::GetInstance()->process_id();
@@ skipping 1626 matching lines @@
 }
 
 ScopedTraceBinaryEfficient::~ScopedTraceBinaryEfficient() {
   if (*category_group_enabled_) {
     TRACE_EVENT_API_UPDATE_TRACE_EVENT_DURATION(category_group_enabled_,
                                                 name_, event_handle_);
   }
 }
 
 }  // namespace trace_event_internal