[Not for review] Add traces for crbug.com/726626

third_party/WebKit/Source/core/streams/ReadableStreamOperations.cpp

 // Copyright 2015 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 "core/streams/ReadableStreamOperations.h"
 
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/ToV8ForCore.h"
 #include "bindings/core/v8/V8ScriptRunner.h"
 #include "core/streams/UnderlyingSourceBase.h"
 #include "platform/bindings/ScriptState.h"
+#include "platform/instrumentation/tracing/TraceEvent.h"
 
 namespace blink {
 
 ScriptValue ReadableStreamOperations::CreateReadableStream(
     ScriptState* script_state,
     UnderlyingSourceBase* underlying_source,
     ScriptValue strategy) {
+  TRACE_EVENT0("ServiceWorker",
+               "ReadableStreamOperations::CreateReadableStream");
   ScriptState::Scope scope(script_state);
 
   v8::Local<v8::Value> js_underlying_source =
       ToV8(underlying_source, script_state);
   v8::Local<v8::Value> js_strategy = strategy.V8Value();
   v8::Local<v8::Value> args[] = {js_underlying_source, js_strategy};
   return ScriptValue(
       script_state,
       V8ScriptRunner::CallExtraOrCrash(
           script_state, "createReadableStreamWithExternalController", args));
 }
 
 ScriptValue ReadableStreamOperations::CreateCountQueuingStrategy(
     ScriptState* script_state,
     size_t high_water_mark) {
+  TRACE_EVENT0("ServiceWorker",
+               "ReadableStreamOperations::CreateCountQueuingStrategy");
   ScriptState::Scope scope(script_state);
 
   v8::Local<v8::Value> args[] = {
       v8::Number::New(script_state->GetIsolate(), high_water_mark)};
   return ScriptValue(
       script_state,
       V8ScriptRunner::CallExtraOrCrash(
           script_state, "createBuiltInCountQueuingStrategy", args));
 }
 
@@ skipping 129 matching lines @@
       branches->Get(script_state->GetContext(), 0).ToLocalChecked());
   *new_stream2 = ScriptValue(
       script_state,
       branches->Get(script_state->GetContext(), 1).ToLocalChecked());
 
   DCHECK(IsReadableStream(script_state, *new_stream1));
   DCHECK(IsReadableStream(script_state, *new_stream2));
 }
 
 }  // namespace blink