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

third_party/WebKit/Source/modules/fetch/BodyStreamBuffer.cpp

Index: third_party/WebKit/Source/modules/fetch/BodyStreamBuffer.cpp
diff --git a/third_party/WebKit/Source/modules/fetch/BodyStreamBuffer.cpp b/third_party/WebKit/Source/modules/fetch/BodyStreamBuffer.cpp
index a35e4abb23ec351cf59634c0cd2f189174ea91a3..0700734cb78cdd2c731eba6066272e1d38a157f2 100644
--- a/third_party/WebKit/Source/modules/fetch/BodyStreamBuffer.cpp
+++ b/third_party/WebKit/Source/modules/fetch/BodyStreamBuffer.cpp
@@ -18,6 +18,7 @@
 #include "platform/bindings/V8PrivateProperty.h"
 #include "platform/bindings/V8ThrowException.h"
 #include "platform/blob/BlobData.h"
+#include "platform/instrumentation/tracing/TraceEvent.h"
 #include "platform/network/EncodedFormData.h"
 
 namespace blink {
@@ -93,17 +94,27 @@ BodyStreamBuffer::BodyStreamBuffer(ScriptState* script_state,
       script_state_(script_state),
       consumer_(consumer),
       made_from_readable_stream_(false) {
+  TRACE_EVENT0("ServiceWorker", "BodyStreamBuffer::BodyStreamBuffer");
   v8::Local<v8::Value> body_value = ToV8(this, script_state);
   DCHECK(!body_value.IsEmpty());
   DCHECK(body_value->IsObject());
   v8::Local<v8::Object> body = body_value.As<v8::Object>();
 
-  ScriptValue readable_stream = ReadableStreamOperations::CreateReadableStream(
-      script_state, this,
-      ReadableStreamOperations::CreateCountQueuingStrategy(script_state, 0));
+  ScriptValue readable_stream;
+  {
+    TRACE_EVENT0("ServiceWorker",
+                 "BodyStreamBuffer::BodyStreamBuffer CreateReadableStream");
+    readable_stream = ReadableStreamOperations::CreateReadableStream(
+        script_state, this,
+        ReadableStreamOperations::CreateCountQueuingStrategy(script_state, 0));
+  }
   DCHECK(!readable_stream.IsEmpty());
-  V8PrivateProperty::GetInternalBodyStream(script_state->GetIsolate())
-      .Set(body, readable_stream.V8Value());
+  {
+    TRACE_EVENT0("ServiceWorker",
+                 "BodyStreamBuffer::BodyStreamBuffer GetInternalBodyStream");
+    V8PrivateProperty::GetInternalBodyStream(script_state->GetIsolate())
+        .Set(body, readable_stream.V8Value());
+  }
   consumer_->SetClient(this);
   OnStateChange();
 }