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diff --git a/base/win/event_trace_provider.h b/base/win/event_trace_provider.h
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+// Copyright (c) 2009 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.
+//
+// Declaration of a Windows event trace provider class, to allow using
+// Windows Event Tracing for logging transport and control.
+#ifndef BASE_WIN_EVENT_TRACE_PROVIDER_H_
+#define BASE_WIN_EVENT_TRACE_PROVIDER_H_
+#pragma once
+
+#include <windows.h>
+#include <wmistr.h>
+#include <evntrace.h>
+#include "base/basictypes.h"
+
+namespace base {
+namespace win {
+
+typedef GUID EtwEventClass;
+typedef UCHAR EtwEventType;
+typedef UCHAR EtwEventLevel;
+typedef USHORT EtwEventVersion;
+typedef ULONG EtwEventFlags;
+
+// Base class is a POD for correctness.
+template <size_t N> struct EtwMofEventBase {
+  EVENT_TRACE_HEADER header;
+  MOF_FIELD fields[N];
+};
+
+// Utility class to auto-initialize event trace header structures.
+template <size_t N> class EtwMofEvent: public EtwMofEventBase<N> {
+ public:
+  typedef EtwMofEventBase<N> Super;
+
+  EtwMofEvent() {
+    memset(static_cast<Super*>(this), 0, sizeof(Super));
+  }
+
+  EtwMofEvent(const EtwEventClass& event_class, EtwEventType type,
+              EtwEventLevel level) {
+    memset(static_cast<Super*>(this), 0, sizeof(Super));
+    header.Size = sizeof(Super);
+    header.Guid = event_class;
+    header.Class.Type = type;
+    header.Class.Level = level;
+    header.Flags = WNODE_FLAG_TRACED_GUID | WNODE_FLAG_USE_MOF_PTR;
+  }
+
+  EtwMofEvent(const EtwEventClass& event_class, EtwEventType type,
+              EtwEventVersion version, EtwEventLevel level) {
+    memset(static_cast<Super*>(this), 0, sizeof(Super));
+    header.Size = sizeof(Super);
+    header.Guid = event_class;
+    header.Class.Type = type;
+    header.Class.Version = version;
+    header.Class.Level = level;
+    header.Flags = WNODE_FLAG_TRACED_GUID | WNODE_FLAG_USE_MOF_PTR;
+  }
+
+  void SetField(int field, size_t size, const void *data) {
+    // DCHECK(field < N);
+    if ((field < N) && (size <= kuint32max)) {
+      fields[field].DataPtr = reinterpret_cast<ULONG64>(data);
+      fields[field].Length = static_cast<ULONG>(size);
+    }
+  }
+
+  EVENT_TRACE_HEADER* get() { return& header; }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(EtwMofEvent);
+};
+
+// Trace provider with Event Tracing for Windows. The trace provider
+// registers with ETW by its name which is a GUID. ETW calls back to
+// the object whenever the trace level or enable flags for this provider
+// name changes.
+// Users of this class can test whether logging is currently enabled at
+// a particular trace level, and whether particular enable flags are set,
+// before other resources are consumed to generate and issue the log
+// messages themselves.
+class EtwTraceProvider {
+ public:
+  // Creates an event trace provider identified by provider_name, which
+  // will be the name registered with Event Tracing for Windows (ETW).
+  explicit EtwTraceProvider(const GUID& provider_name);
+
+  // Creates an unnamed event trace provider, the provider must be given
+  // a name before registration.
+  EtwTraceProvider();
+  virtual ~EtwTraceProvider();
+
+  // Registers the trace provider with Event Tracing for Windows.
+  // Note: from this point forward ETW may call the provider's control
+  //    callback. If the provider's name is enabled in some trace session
+  //    already, the callback may occur recursively from this call, so
+  //    call this only when you're ready to handle callbacks.
+  ULONG Register();
+  // Unregisters the trace provider with ETW.
+  ULONG Unregister();
+
+  // Accessors.
+  void set_provider_name(const GUID& provider_name) {
+    provider_name_ = provider_name;
+  }
+  const GUID& provider_name() const { return provider_name_; }
+  TRACEHANDLE registration_handle() const { return registration_handle_; }
+  TRACEHANDLE session_handle() const { return session_handle_; }
+  EtwEventFlags enable_flags() const { return enable_flags_; }
+  EtwEventLevel enable_level() const { return enable_level_; }
+
+  // Returns true iff logging should be performed for "level" and "flags".
+  // Note: flags is treated as a bitmask, and should normally have a single
+  //      bit set, to test whether to log for a particular sub "facility".
+  bool ShouldLog(EtwEventLevel level, EtwEventFlags flags) {
+    return NULL != session_handle_ && level >= enable_level_ &&
+        (0 != (flags & enable_flags_));
+  }
+
+  // Simple wrappers to log Unicode and ANSI strings.
+  // Do nothing if !ShouldLog(level, 0xFFFFFFFF).
+  ULONG Log(const EtwEventClass& event_class, EtwEventType type,
+            EtwEventLevel level, const char *message);
+  ULONG Log(const EtwEventClass& event_class, EtwEventType type,
+            EtwEventLevel level, const wchar_t *message);
+
+  // Log the provided event.
+  ULONG Log(EVENT_TRACE_HEADER* event);
+
+ protected:
+  // Called after events have been enabled, override in subclasses
+  // to set up state or log at the start of a session.
+  // Note: This function may be called ETW's thread and may be racy,
+  //    bring your own locking if needed.
+  virtual void OnEventsEnabled() {}
+
+  // Called just before events are disabled, override in subclasses
+  // to tear down state or log at the end of a session.
+  // Note: This function may be called ETW's thread and may be racy,
+  //    bring your own locking if needed.
+  virtual void OnEventsDisabled() {}
+
+  // Called just after events have been disabled, override in subclasses
+  // to tear down state at the end of a session. At this point it's
+  // to late to log anything to the session.
+  // Note: This function may be called ETW's thread and may be racy,
+  //    bring your own locking if needed.
+  virtual void PostEventsDisabled() {}
+
+ private:
+  ULONG EnableEvents(PVOID buffer);
+  ULONG DisableEvents();
+  ULONG Callback(WMIDPREQUESTCODE request, PVOID buffer);
+  static ULONG WINAPI ControlCallback(WMIDPREQUESTCODE request, PVOID context,
+                                      ULONG *reserved, PVOID buffer);
+
+  GUID provider_name_;
+  TRACEHANDLE registration_handle_;
+  TRACEHANDLE session_handle_;
+  EtwEventFlags enable_flags_;
+  EtwEventLevel enable_level_;
+
+  // We don't use this, but on XP we're obliged to pass one in to
+  // RegisterTraceGuids. Non-const, because that's how the API needs it.
+  static TRACE_GUID_REGISTRATION obligatory_guid_registration_;
+
+  DISALLOW_COPY_AND_ASSIGN(EtwTraceProvider);
+};
+
+}  // namespace win
+}  // namespace base
+
+#endif  // BASE_WIN_EVENT_TRACE_PROVIDER_H_