[Tracing] V8 Tracing Controller - Fix async trace event bug

Usage of hex IO manipulator for async event IDs corrupts future decimal number
outputs.

BUG=v8:5261

Review-Url: https://codereview.chromium.org/2200113003
Cr-Commit-Position: refs/heads/master@{#38331}

src/libplatform/tracing/trace-writer.cc

@@ -107,7 +107,8 @@ void JSONTraceWriter::AppendTraceEvent(TraceObject* trace_event) {
       stream_ << ",\"scope\":\"" << trace_event->scope() << "\"";
     }
     // So as not to lose bits from a 64-bit integer, output as a hex string.
-    stream_ << ",\"id\":\"0x" << std::hex << trace_event->id() << "\"";
+    stream_ << ",\"id\":\"0x" << std::hex << trace_event->id() << "\""
+            << std::dec;
   }
   stream_ << ",\"args\":{";
   const char** arg_names = trace_event->arg_names();

test/cctest/libplatform/test-tracing.cc

@@ -128,8 +128,8 @@ TEST(TestJSONTraceWriter) {
     TraceObject trace_object;
     trace_object.InitializeForTesting(
         'X', tracing_controller.GetCategoryGroupEnabled("v8-cat"), "Test0",
-        v8::internal::tracing::kGlobalScope, 42, 123, 0, NULL, NULL, NULL, 0,
-        11, 22, 100, 50, 33, 44);
+        v8::internal::tracing::kGlobalScope, 42, 123, 0, NULL, NULL, NULL,
+        TRACE_EVENT_FLAG_HAS_ID, 11, 22, 100, 50, 33, 44);
     writer->AppendTraceEvent(&trace_object);
     trace_object.InitializeForTesting(
         'Y', tracing_controller.GetCategoryGroupEnabled("v8-cat"), "Test1",
@@ -143,9 +143,9 @@ TEST(TestJSONTraceWriter) {
   std::string expected_trace_str =
       "{\"traceEvents\":[{\"pid\":11,\"tid\":22,\"ts\":100,\"tts\":50,"
       "\"ph\":\"X\",\"cat\":\"v8-cat\",\"name\":\"Test0\",\"dur\":33,"
-      "\"tdur\":44,\"args\":{}},{\"pid\":55,\"tid\":66,\"ts\":110,\"tts\":55,"
-      "\"ph\":\"Y\",\"cat\":\"v8-cat\",\"name\":\"Test1\",\"dur\":77,"
-      "\"tdur\":88,\"args\":{}}]}";
+      "\"tdur\":44,\"id\":\"0x2a\",\"args\":{}},{\"pid\":55,\"tid\":66,"
+      "\"ts\":110,\"tts\":55,\"ph\":\"Y\",\"cat\":\"v8-cat\",\"name\":"
+      "\"Test1\",\"dur\":77,\"tdur\":88,\"args\":{}}]}";
 
   CHECK_EQ(expected_trace_str, trace_str);