Add DeadlineOverrun step to the RendererSchedulerIdlePeriod trace event.

content/renderer/scheduler/renderer_scheduler_impl.cc

 // Copyright 2014 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/scheduler/renderer_scheduler_impl.h"
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop_proxy.h"
 #include "base/trace_event/trace_event.h"
 #include "base/trace_event/trace_event_argument.h"
@@ skipping 275 matching lines @@
 void RendererSchedulerImpl::StartIdlePeriod() {
   TRACE_EVENT_ASYNC_BEGIN0("renderer.scheduler",
                            "RendererSchedulerIdlePeriod", this);
   DCHECK(main_thread_checker_.CalledOnValidThread());
   renderer_task_queue_selector_->EnableQueue(
       IDLE_TASK_QUEUE, RendererTaskQueueSelector::BEST_EFFORT_PRIORITY);
   task_queue_manager_->PumpQueue(IDLE_TASK_QUEUE);
 }
 
 void RendererSchedulerImpl::EndIdlePeriod() {
+  bool is_tracing;
+  TRACE_EVENT_CATEGORY_GROUP_ENABLED("renderer.scheduler", &is_tracing);
+  if (is_tracing && !estimated_next_frame_begin_.is_null() &&
+      base::TimeTicks::Now() > estimated_next_frame_begin_) {
+    TRACE_EVENT_ASYNC_STEP_INTO_WITH_TIMESTAMP0(
+        "renderer.scheduler",
+        "RendererSchedulerIdlePeriod",
+        this,
+        "DeadlineOverrun",
+        estimated_next_frame_begin_.ToInternalValue());
+  }
   TRACE_EVENT_ASYNC_END0("renderer.scheduler",
                          "RendererSchedulerIdlePeriod", this);
   DCHECK(main_thread_checker_.CalledOnValidThread());
   end_idle_period_closure_.Cancel();
   renderer_task_queue_selector_->DisableQueue(IDLE_TASK_QUEUE);
 }
 
 void RendererSchedulerImpl::SetTimeSourceForTesting(
     scoped_refptr<cc::TestNowSource> time_source) {
   DCHECK(main_thread_checker_.CalledOnValidThread());
@@ skipping 123 matching lines @@
       // meaningful touchstart response and should not impact task priority.
       return current_state;
 
     default:
       break;
   }
   return INPUT_ACTIVE;
 }
 
 }  // namespace content