Event tracing for sync events

chrome/browser/sync/glue/data_type_manager_impl.cc

Index: chrome/browser/sync/glue/data_type_manager_impl.cc
diff --git a/chrome/browser/sync/glue/data_type_manager_impl.cc b/chrome/browser/sync/glue/data_type_manager_impl.cc
index 2d49be4b85407ad635ab8ebf14ccba40aa9b8796..810705a71af27f325478301a3448370770710b8b 100644
--- a/chrome/browser/sync/glue/data_type_manager_impl.cc
+++ b/chrome/browser/sync/glue/data_type_manager_impl.cc
@@ -10,6 +10,7 @@
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/compiler_specific.h"
+#include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "base/metrics/histogram.h"
@@ -293,6 +294,8 @@ void DataTypeManagerImpl::StartNextType() {
   // front of the list.
   if (!needs_start_.empty()) {
     VLOG(1) << "Starting " << needs_start_[0]->name();
+    TRACE_EVENT_BEGIN1("sync", "ModelAssociation",

[jbates, 2011/11/16 00:46:57]

Does this show up OK in about:tracing? BEGIN..END pairs are assumed to occur in
one scope by about:tracing, so this might not look correct. Another thing to
note is that about:tracing only shows the begin event's arguments.

We have a bug filed to address this (ie: add START/FINISH events that have no
scoping assumptions http://code.google.com/p/chromium/issues/detail?id=100131).
I'm working on this now, but it will also require updates to the UI to display
global start/finish events in a unique way. Feel free to move forward with this
as is if it's working for you and we can patch it up later.

[rlarocque, 2011/11/16 01:03:40]

That's odd.  The results I see in about:tracing seem to make sense.  

I will remove the matching END's arguments.

+                       "DataType", ModelTypeToCharPtr(needs_start_[0]->type()));
     needs_start_[0]->Start(
         NewCallback(this, &DataTypeManagerImpl::TypeStartCallback));
     return;
@@ -332,6 +335,9 @@ void DataTypeManagerImpl::TypeStartCallback(
   // on the UI thread.
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
+  TRACE_EVENT_END1("sync", "ModelAssociation",
+                   "DataType", ModelTypeToCharPtr(needs_start_[0]->type()));
+
   if (state_ == STOPPING) {
     // If we reach this callback while stopping, this means that
     // DataTypeManager::Stop() was called while the current data type