Add trace event to V8 compiler API.

BUG=chromium:626256
LOG=NO

Review-Url: https://codereview.chromium.org/2126193002
Cr-Commit-Position: refs/heads/master@{#37578}

src/api.cc

@@ -1918,6 +1918,7 @@ MaybeLocal<UnboundScript> ScriptCompiler::CompileUnboundInternal(
   i::Isolate* isolate = reinterpret_cast<i::Isolate*>(v8_isolate);
   PREPARE_FOR_EXECUTION_WITH_ISOLATE(isolate, ScriptCompiler, CompileUnbound,
                                      UnboundScript);
+  TRACE_EVENT0("v8", "V8.ScriptCompiler");
 
   // Don't try to produce any kind of cache when the debugger is loaded.
   if (isolate->debug()->is_loaded() &&
@@ -2078,6 +2079,7 @@ MaybeLocal<Function> ScriptCompiler::CompileFunctionInContext(
     Local<Object> context_extensions[]) {
   PREPARE_FOR_EXECUTION(v8_context, ScriptCompiler, CompileFunctionInContext,
                         Function);
+  TRACE_EVENT0("v8", "V8.ScriptCompiler");
   i::Handle<i::String> source_string;
   auto factory = isolate->factory();
   if (arguments_count) {
@@ -2192,6 +2194,7 @@ MaybeLocal<Script> ScriptCompiler::Compile(Local<Context> context,
                                            Local<String> full_source_string,
                                            const ScriptOrigin& origin) {
   PREPARE_FOR_EXECUTION(context, ScriptCompiler, Compile, Script);
+  TRACE_EVENT0("v8", "V8.ScriptCompiler");
   i::StreamedSource* source = v8_source->impl();
   i::Handle<i::String> str = Utils::OpenHandle(*(full_source_string));
   i::Handle<i::Script> script = isolate->factory()->NewScript(str);