Add devtools trace events for Timeline Program notification

Source/web/WebDevToolsAgentImpl.cpp

Index: Source/web/WebDevToolsAgentImpl.cpp
diff --git a/Source/web/WebDevToolsAgentImpl.cpp b/Source/web/WebDevToolsAgentImpl.cpp
index 19452d4586794d85e075d849d691ba1b709a69eb..e27e8b837a2fdcbef726fbb548988305f24e8607 100644
--- a/Source/web/WebDevToolsAgentImpl.cpp
+++ b/Source/web/WebDevToolsAgentImpl.cpp
@@ -675,6 +675,7 @@ void WebDevToolsAgentImpl::willProcessTask()
         return;
     if (InspectorController* ic = inspectorController())
         ic->willProcessTask();
+    TRACE_EVENT_BEGIN0(TRACE_DISABLED_BY_DEFAULT("devtools.timeline"), "Program");
 }
 
 void WebDevToolsAgentImpl::didProcessTask()
@@ -683,6 +684,7 @@ void WebDevToolsAgentImpl::didProcessTask()
         return;
     if (InspectorController* ic = inspectorController())
         ic->didProcessTask();
+    TRACE_EVENT_END0(TRACE_DISABLED_BY_DEFAULT("devtools.timeline"), "Program");
     flushPendingFrontendMessages();
 }