Independently enable recording and event callback

content/renderer/devtools/devtools_agent.cc

Index: content/renderer/devtools/devtools_agent.cc
diff --git a/content/renderer/devtools/devtools_agent.cc b/content/renderer/devtools/devtools_agent.cc
index a0693e519eb803f889e30d485ffea8d7d403f310..4115c8418a7fbbe4c1eb64dff76477b4df0960e2 100644
--- a/content/renderer/devtools/devtools_agent.cc
+++ b/content/renderer/devtools/devtools_agent.cc
@@ -82,6 +82,7 @@ DevToolsAgent::DevToolsAgent(RenderViewImpl* render_view)
 
 DevToolsAgent::~DevToolsAgent() {
   g_agent_for_routing_id.Get().erase(routing_id());
+  setTraceEventCallback(NULL);
 }
 
 // Called on the Renderer thread.
@@ -137,15 +138,13 @@ void DevToolsAgent::clearBrowserCookies() {
 
 void DevToolsAgent::setTraceEventCallback(TraceEventCallback cb) {
   TraceLog* trace_log = TraceLog::GetInstance();
-  trace_log->SetEventCallback(cb ? TraceEventCallbackWrapper : 0);
   base::subtle::NoBarrier_Store(&event_callback_,
                                 reinterpret_cast<base::subtle::AtomicWord>(cb));
   if (!!cb) {
-    trace_log->SetEnabled(base::debug::CategoryFilter(
-        base::debug::CategoryFilter::kDefaultCategoryFilterString),
-        TraceLog::RECORD_UNTIL_FULL);
+    trace_log->SetEventCallbackEnabled(base::debug::CategoryFilter(""),

[caseq, 2013/11/19 18:32:29]

Why did we stop using the default filter here? I think we rather want to
eventually narrow down the category filter here, expanding it to include
categories disable by default may slow things down.

[dsinclair, 2013/11/19 18:39:11]

This won't enable disabled-by-default-. Those will only be enabled if you
explicitly put them into the category string. This will enable the Debug and
Test categories that are removed as part of the default category filter.

[Xianzhu, 2013/11/19 18:39:21]

Actually CategoryFilter("") will create a default filter. However I changed back
to the original code which seems clearer.

+                                       cb ? TraceEventCallbackWrapper : 0);
   } else {
-    trace_log->SetDisabled();
+    trace_log->SetEventCallbackDisabled();
   }
 }