Slow Reports - Add message filter to trigger background traces from child processes.

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 7b1452f982d1f0700fbf16cc553ba7011bdaa8c3..6c67dd3359639c648c73cead6fd842d5bd58b4dc 100644
--- a/content/browser/tracing/tracing_controller_impl.cc
+++ b/content/browser/tracing/tracing_controller_impl.cc
@@ -484,6 +484,8 @@ void TracingControllerImpl::AddTraceMessageFilter(
     trace_message_filter->SendEnableMonitoring(
         TraceLog::GetInstance()->GetCurrentTraceConfig());
   }
+  if (!trace_message_filter_added_callback_.is_null())
+    trace_message_filter_added_callback_.Run(trace_message_filter);
 }
 
 void TracingControllerImpl::RemoveTraceMessageFilter(
@@ -825,6 +827,18 @@ bool TracingControllerImpl::IsCoordinatorProcess() const {
   return true;
 }
 
+void TracingControllerImpl::SetTraceMessageFilterAddedCallback(
+    const TraceMessageFilterAddedCallback& callback) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  trace_message_filter_added_callback_ = callback;
+}
+
+void TracingControllerImpl::GetTraceMessageFilters(
+    TraceMessageFilterSet* filters) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  filters->insert(trace_message_filters_.begin(), trace_message_filters_.end());
+}
+
 void TracingControllerImpl::OnProcessMemoryDumpResponse(
     TraceMessageFilter* trace_message_filter,
     uint64 dump_guid,