Add a sampling tracing to RenderWidget::DoDeferredUpdate

content/renderer/render_widget.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/render_widget.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
@@ skipping 1081 matching lines @@
 
 void RenderWidget::DoDeferredUpdateAndSendInputAck() {
   DoDeferredUpdate();
 
   if (pending_input_event_ack_)
     Send(pending_input_event_ack_.release());
 }
 
 void RenderWidget::DoDeferredUpdate() {
   TRACE_EVENT0("renderer", "RenderWidget::DoDeferredUpdate");
+// Not supported in split-dll build. http://crbug.com/237249

[nduca, 2013/07/03 05:34:24]

why? the bug you link is the catch all bug. If a trace event feature doesn't
work in split dll, we should have a bug specific to that and have identified if
it will never work, or (hopefully) is just a temporary thing. And if its a
temporary thing, who owns resolving it.

[haraken, 2013/07/03 07:33:15]

Done.

+#if !defined(CHROME_SPLIT_DLL)
+  TraceEventSamplingState0Scope samplingScope("Chrome\0Paint");

[nduca, 2013/07/03 05:34:24]

What is the null character's role in this? How does this get handled?

[haraken, 2013/07/03 07:33:15]

It means "category\0name". This is the normal format of trace events and already
handled in the current implementation.

But I changed the macro so that we can write it as follows:

  TRACE_EVENT_SAMPLING_STATE_SCOPE("Chrome", "Paint");

+#endif
 
   if (!webwidget_)
     return;
 
   if (!init_complete_) {
     TRACE_EVENT0("renderer", "EarlyOut_InitNotComplete");
     return;
   }
   if (update_reply_pending_) {
     TRACE_EVENT0("renderer", "EarlyOut_UpdateReplyPending");
@@ skipping 1296 matching lines @@
 
   if (!context->InitializeWithDefaultBufferSizes(
           attributes,
           false /* bind generates resources */,
           CAUSE_FOR_GPU_LAUNCH_WEBGRAPHICSCONTEXT3DCOMMANDBUFFERIMPL_INITIALIZE))
     return NULL;
   return context.release();
 }
 
 }  // namespace content