[ETW Export] Add polling for ETW keyword.

base/trace_event/trace_log.cc

 // Copyright 2015 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/trace_event/trace_log.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "base/base_switches.h"
@@ skipping 1689 matching lines @@
   else if (options & kInternalEchoToConsole)
     return TraceBuffer::CreateTraceBufferRingBuffer(
         kEchoToConsoleTraceEventBufferChunks);
   else if (options & kInternalRecordAsMuchAsPossible)
     return TraceBuffer::CreateTraceBufferVectorOfSize(
         kTraceEventVectorBigBufferChunks);
   return TraceBuffer::CreateTraceBufferVectorOfSize(
       kTraceEventVectorBufferChunks);
 }
 
+#if defined(OS_WIN)
+void TraceLog::UpdateETWCategoryGroupEnabledFlags() {
+  AutoLock lock(lock_);
+  size_t category_index = base::subtle::NoBarrier_Load(&g_category_index);
+  // Go through each category and set/clear the ETW bit depending on whether the
+  // category is enabled.
+  for (size_t i = 0; i < category_index; i++) {
+    const char* category_group = g_category_groups[i];
+    DCHECK(category_group);
+    if (base::trace_event::TraceEventETWExport::IsCategoryGroupEnabled(
+            category_group)) {
+      g_category_group_enabled[category_index] |= ENABLED_FOR_ETW_EXPORT;
+    } else {
+      g_category_group_enabled[category_index] &= ~ENABLED_FOR_ETW_EXPORT;
+    }
+  }
+}
+#endif  // defined(OS_WIN)
+
 void ConvertableToTraceFormat::EstimateTraceMemoryOverhead(
     TraceEventMemoryOverhead* overhead) {
   overhead->Add("ConvertableToTraceFormat(Unknown)", sizeof(*this));
 }
 
 }  // namespace trace_event
 }  // namespace base
 
 namespace trace_event_internal {
 
@@ skipping 26 matching lines @@
 }
 
 ScopedTraceBinaryEfficient::~ScopedTraceBinaryEfficient() {
   if (*category_group_enabled_) {
     TRACE_EVENT_API_UPDATE_TRACE_EVENT_DURATION(category_group_enabled_, name_,
                                                 event_handle_);
   }
 }
 
 }  // namespace trace_event_internal