Add a sampling tracing to RenderWidget::DoDeferredUpdate

base/debug/trace_event_impl.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 "base/debug/trace_event_impl.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/debug/leak_annotations.h"
@@ skipping 25 matching lines @@
  public:
   static void Delete() {
     Singleton<base::debug::TraceLog,
               StaticMemorySingletonTraits<base::debug::TraceLog> >::OnExit(0);
   }
 };
 
 // Not supported in split-dll build. http://crbug.com/237249
 #if !defined(CHROME_SPLIT_DLL)
 // The thread buckets for the sampling profiler.
-BASE_EXPORT TRACE_EVENT_API_ATOMIC_WORD g_trace_state0;
-BASE_EXPORT TRACE_EVENT_API_ATOMIC_WORD g_trace_state1;
-BASE_EXPORT TRACE_EVENT_API_ATOMIC_WORD g_trace_state2;
+BASE_EXPORT TRACE_EVENT_API_ATOMIC_WORD g_trace_state[3];
 #endif
 
 namespace base {
 namespace debug {
 
 // Controls the number of trace events we will buffer in-memory
 // before throwing them away.
 const size_t kTraceEventBufferSize = 500000;
 const size_t kTraceEventBatchSize = 1000;
 const size_t kTraceEventInitialBufferSize = 1024;
@@ skipping 882 matching lines @@
     num_traces_recorded_++;
 
     category_filter_ = CategoryFilter(category_filter);
     EnableIncludedCategoryGroups();
 
     // Not supported in split-dll build. http://crbug.com/237249
   #if !defined(CHROME_SPLIT_DLL)
     if (options & ENABLE_SAMPLING) {
       sampling_thread_.reset(new TraceSamplingThread);
       sampling_thread_->RegisterSampleBucket(
-          &g_trace_state0,
+          &g_trace_state[0],
           "bucket0",
           Bind(&TraceSamplingThread::DefaultSampleCallback));
       sampling_thread_->RegisterSampleBucket(
-          &g_trace_state1,
+          &g_trace_state[1],
           "bucket1",
           Bind(&TraceSamplingThread::DefaultSampleCallback));
       sampling_thread_->RegisterSampleBucket(
-          &g_trace_state2,
+          &g_trace_state[2],
           "bucket2",
           Bind(&TraceSamplingThread::DefaultSampleCallback));
       if (!PlatformThread::Create(
             0, sampling_thread_.get(), &sampling_thread_handle_)) {
         DCHECK(false) << "failed to create thread";
       }
     }
   #endif
 
     dispatching_to_observer_list_ = true;
@@ skipping 579 matching lines @@
         0,                       // num_args
         NULL,                    // arg_names
         NULL,                    // arg_types
         NULL,                    // arg_values
         NULL,                    // convertable values
         TRACE_EVENT_FLAG_NONE);  // flags
   }
 }
 
 }  // namespace trace_event_internal