gin: Use V8 Maybe APIs

gin/try_catch.cc

 // Copyright 2013 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 "gin/try_catch.h"
 
 #include <sstream>
 
 #include "gin/converter.h"
 
+namespace {
+
+v8::Local<v8::String> GetSourceLine(v8::Isolate* isolate,
+                                    v8::Local<v8::Message> message) {
+  auto maybe = message->GetSourceLine(isolate->GetCurrentContext());
+  v8::Local<v8::String> source_line;
+  return maybe.ToLocal(&source_line) ? source_line : v8::String::Empty(isolate);
+}
+
+}  // namespace
+
 namespace gin {
 
-TryCatch::TryCatch() {
+TryCatch::TryCatch(v8::Isolate* isolate)
+    : isolate_(isolate), try_catch_(isolate) {
 }
 
 TryCatch::~TryCatch() {
 }
 
 bool TryCatch::HasCaught() {
   return try_catch_.HasCaught();
 }
 
 std::string TryCatch::GetStackTrace() {
   if (!HasCaught()) {
     return "";
   }
 
   std::stringstream ss;
   v8::Local<v8::Message> message = try_catch_.Message();
   ss << V8ToString(message->Get()) << std::endl
-     << V8ToString(message->GetSourceLine()) << std::endl;
+     << V8ToString(GetSourceLine(isolate_, message)) << std::endl;
 
   v8::Local<v8::StackTrace> trace = message->GetStackTrace();
   if (trace.IsEmpty())
     return ss.str();
 
   int len = trace->GetFrameCount();
   for (int i = 0; i < len; ++i) {
     v8::Local<v8::StackFrame> frame = trace->GetFrame(i);
     ss << V8ToString(frame->GetScriptName()) << ":"
        << frame->GetLineNumber() << ":"
        << frame->GetColumn() << ": "
        << V8ToString(frame->GetFunctionName())
        << std::endl;
   }
   return ss.str();
 }
 
 }  // namespace gin