Implement sampling profiler (chromium side change)

content/browser/tracing/tracing_controller_impl.cc

Index: content/browser/tracing/tracing_controller_impl.cc
diff --git a/content/browser/tracing/tracing_controller_impl.cc b/content/browser/tracing/tracing_controller_impl.cc
index ba9f2e01ab1b88fe1104f123b98191e0b02d9087..ff025142f6b8de0a7444f4630eeed212ff963303 100644
--- a/content/browser/tracing/tracing_controller_impl.cc
+++ b/content/browser/tracing/tracing_controller_impl.cc
@@ -80,7 +80,7 @@ void TracingControllerImpl::ResultFile::OpenTask() {
 
 void TracingControllerImpl::ResultFile::WriteTask(
     const scoped_refptr<base::RefCountedString>& events_str_ptr) {
-  if (!file_)
+  if (!file_ || !events_str_ptr->data().size())
     return;
 
   // If there is already a result in the file, then put a commma
@@ -423,7 +423,7 @@ void TracingControllerImpl::AddTraceMessageFilter(
     trace_message_filter->SendSetWatchEvent(watch_category_name_,
                                             watch_event_name_);
   }
-  if (can_disable_recording()) {
+  if (can_disable_recording() || can_disable_monitoring()) {
     trace_message_filter->SendBeginTracing(
         TraceLog::GetInstance()->GetCurrentCategoryFilter().ToString(),
         TraceLog::GetInstance()->trace_options());