Move TraceEvent.h from platform/ to wtf/

Source/platform/TraceEvent.h

-/*
- * Copyright (C) 2011 Google Inc. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1.  Redistributions of source code must retain the above copyright
- *     notice, this list of conditions and the following disclaimer.
- * 2.  Redistributions in binary form must reproduce the above copyright
- *     notice, this list of conditions and the following disclaimer in the
- *     documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
- * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
- * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
- * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
- * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-// Trace events are for tracking application performance and resource usage.
-// Macros are provided to track:
-//    Begin and end of function calls
-//    Counters
-//
-// Events are issued against categories. Whereas LOG's
-// categories are statically defined, TRACE categories are created
-// implicitly with a string. For example:
-//   TRACE_EVENT_INSTANT0("MY_SUBSYSTEM", "SomeImportantEvent")
-//
-// Events can be INSTANT, or can be pairs of BEGIN and END in the same scope:
-//   TRACE_EVENT_BEGIN0("MY_SUBSYSTEM", "SomethingCostly")
-//   doSomethingCostly()
-//   TRACE_EVENT_END0("MY_SUBSYSTEM", "SomethingCostly")
-// Note: our tools can't always determine the correct BEGIN/END pairs unless
-// these are used in the same scope. Use ASYNC_BEGIN/ASYNC_END macros if you need them
-// to be in separate scopes.
-//
-// A common use case is to trace entire function scopes. This
-// issues a trace BEGIN and END automatically:
-//   void doSomethingCostly() {
-//     TRACE_EVENT0("MY_SUBSYSTEM", "doSomethingCostly");
-//     ...
-//   }
-//
-// Additional parameters can be associated with an event:
-//   void doSomethingCostly2(int howMuch) {
-//     TRACE_EVENT1("MY_SUBSYSTEM", "doSomethingCostly",
-//         "howMuch", howMuch);
-//     ...
-//   }
-//
-// The trace system will automatically add to this information the
-// current process id, thread id, and a timestamp in microseconds.
-//
-// To trace an asynchronous procedure such as an IPC send/receive, use ASYNC_BEGIN and
-// ASYNC_END:
-//   [single threaded sender code]
-//     static int send_count = 0;
-//     ++send_count;
-//     TRACE_EVENT_ASYNC_BEGIN0("ipc", "message", send_count);
-//     Send(new MyMessage(send_count));
-//   [receive code]
-//     void OnMyMessage(send_count) {
-//       TRACE_EVENT_ASYNC_END0("ipc", "message", send_count);
-//     }
-// The third parameter is a unique ID to match ASYNC_BEGIN/ASYNC_END pairs.
-// ASYNC_BEGIN and ASYNC_END can occur on any thread of any traced process. Pointers can
-// be used for the ID parameter, and they will be mangled internally so that
-// the same pointer on two different processes will not match. For example:
-//   class MyTracedClass {
-//    public:
-//     MyTracedClass() {
-//       TRACE_EVENT_ASYNC_BEGIN0("category", "MyTracedClass", this);
-//     }
-//     ~MyTracedClass() {
-//       TRACE_EVENT_ASYNC_END0("category", "MyTracedClass", this);
-//     }
-//   }
-//
-// Trace event also supports counters, which is a way to track a quantity
-// as it varies over time. Counters are created with the following macro:
-//   TRACE_COUNTER1("MY_SUBSYSTEM", "myCounter", g_myCounterValue);
-//
-// Counters are process-specific. The macro itself can be issued from any
-// thread, however.
-//
-// Sometimes, you want to track two counters at once. You can do this with two
-// counter macros:
-//   TRACE_COUNTER1("MY_SUBSYSTEM", "myCounter0", g_myCounterValue[0]);
-//   TRACE_COUNTER1("MY_SUBSYSTEM", "myCounter1", g_myCounterValue[1]);
-// Or you can do it with a combined macro:
-//   TRACE_COUNTER2("MY_SUBSYSTEM", "myCounter",
-//       "bytesPinned", g_myCounterValue[0],
-//       "bytesAllocated", g_myCounterValue[1]);
-// This indicates to the tracing UI that these counters should be displayed
-// in a single graph, as a summed area chart.
-//
-// Since counters are in a global namespace, you may want to disembiguate with a
-// unique ID, by using the TRACE_COUNTER_ID* variations.
-//
-// By default, trace collection is compiled in, but turned off at runtime.
-// Collecting trace data is the responsibility of the embedding
-// application. In Chrome's case, navigating to about:tracing will turn on
-// tracing and display data collected across all active processes.
-//
-//
-// Memory scoping note:
-// Tracing copies the pointers, not the string content, of the strings passed
-// in for category, name, and arg_names. Thus, the following code will
-// cause problems:
-//     char* str = strdup("impprtantName");
-//     TRACE_EVENT_INSTANT0("SUBSYSTEM", str);  // BAD!
-//     free(str);                   // Trace system now has dangling pointer
-//
-// To avoid this issue with the |name| and |arg_name| parameters, use the
-// TRACE_EVENT_COPY_XXX overloads of the macros at additional runtime overhead.
-// Notes: The category must always be in a long-lived char* (i.e. static const).
-//        The |arg_values|, when used, are always deep copied with the _COPY
-//        macros.
-//
-// When are string argument values copied:
-// const char* arg_values are only referenced by default:
-//     TRACE_EVENT1("category", "name",
-//                  "arg1", "literal string is only referenced");
-// Use TRACE_STR_COPY to force copying of a const char*:
-//     TRACE_EVENT1("category", "name",
-//                  "arg1", TRACE_STR_COPY("string will be copied"));
-// std::string arg_values are always copied:
-//     TRACE_EVENT1("category", "name",
-//                  "arg1", std::string("string will be copied"));
-//
-//
-// Thread Safety:
-// A thread safe singleton and mutex are used for thread safety. Category
-// enabled flags are used to limit the performance impact when the system
-// is not enabled.
-//
-// TRACE_EVENT macros first cache a pointer to a category. The categories are
-// statically allocated and safe at all times, even after exit. Fetching a
-// category is protected by the TraceLog::lock_. Multiple threads initializing
-// the static variable is safe, as they will be serialized by the lock and
-// multiple calls will return the same pointer to the category.
-//
-// Then the category_enabled flag is checked. This is a unsigned char, and
-// not intended to be multithread safe. It optimizes access to addTraceEvent
-// which is threadsafe internally via TraceLog::lock_. The enabled flag may
-// cause some threads to incorrectly call or skip calling addTraceEvent near
-// the time of the system being enabled or disabled. This is acceptable as
-// we tolerate some data loss while the system is being enabled/disabled and
-// because addTraceEvent is threadsafe internally and checks the enabled state
-// again under lock.
-//
-// Without the use of these static category pointers and enabled flags all
-// trace points would carry a significant performance cost of aquiring a lock
-// and resolving the category.
-
-#ifndef TraceEvent_h
-#define TraceEvent_h
-
-#include "platform/EventTracer.h"
-
-#include "wtf/DynamicAnnotations.h"
-#include "wtf/text/CString.h"
-
-// By default, const char* argument values are assumed to have long-lived scope
-// and will not be copied. Use this macro to force a const char* to be copied.
-#define TRACE_STR_COPY(str) \
-    WebCore::TraceEvent::TraceStringWithCopy(str)
-
-// By default, uint64 ID argument values are not mangled with the Process ID in
-// TRACE_EVENT_ASYNC macros. Use this macro to force Process ID mangling.
-#define TRACE_ID_MANGLE(id) \
-    TraceID::ForceMangle(id)
-
-// By default, pointers are mangled with the Process ID in TRACE_EVENT_ASYNC
-// macros. Use this macro to prevent Process ID mangling.
-#define TRACE_ID_DONT_MANGLE(id) \
-    TraceID::DontMangle(id)
-
-// Records a pair of begin and end events called "name" for the current
-// scope, with 0, 1 or 2 associated arguments. If the category is not
-// enabled, then this does nothing.
-// - category and name strings must have application lifetime (statics or
-//   literals). They may not include " chars.
-#define TRACE_EVENT0(category, name) \
-    INTERNAL_TRACE_EVENT_ADD_SCOPED(category, name)
-#define TRACE_EVENT1(category, name, arg1_name, arg1_val) \
-    INTERNAL_TRACE_EVENT_ADD_SCOPED(category, name, arg1_name, arg1_val)
-#define TRACE_EVENT2(category, name, arg1_name, arg1_val, arg2_name, arg2_val) \
-    INTERNAL_TRACE_EVENT_ADD_SCOPED(category, name, arg1_name, arg1_val, \
-        arg2_name, arg2_val)
-
-// Records a single event called "name" immediately, with 0, 1 or 2
-// associated arguments. If the category is not enabled, then this
-// does nothing.
-// - category and name strings must have application lifetime (statics or
-//   literals). They may not include " chars.
-#define TRACE_EVENT_INSTANT0(category, name) \
-    INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_INSTANT, \
-        category, name, TRACE_EVENT_FLAG_NONE)
-#define TRACE_EVENT_INSTANT1(category, name, arg1_name, arg1_val) \
-    INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_INSTANT, \
-        category, name, TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val)
-#define TRACE_EVENT_INSTANT2(category, name, arg1_name, arg1_val, \
-        arg2_name, arg2_val) \
-    INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_INSTANT, \
-        category, name, TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val, \
-        arg2_name, arg2_val)
-#define TRACE_EVENT_COPY_INSTANT0(category, name) \
-    INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_INSTANT, \
-        category, name, TRACE_EVENT_FLAG_COPY)
-#define TRACE_EVENT_COPY_INSTANT1(category, name, arg1_name, arg1_val) \
-    INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_INSTANT, \
-        category, name, TRACE_EVENT_FLAG_COPY, arg1_name, arg1_val)
-#define TRACE_EVENT_COPY_INSTANT2(category, name, arg1_name, arg1_val, \
-        arg2_name, arg2_val) \
-    INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_INSTANT, \
-        category, name, TRACE_EVENT_FLAG_COPY, arg1_name, arg1_val, \
-        arg2_name, arg2_val)
-
-// Records a single BEGIN event called "name" immediately, with 0, 1 or 2
-// associated arguments. If the category is not enabled, then this
-// does nothing.
-// - category and name strings must have application lifetime (statics or
-//   literals). They may not include " chars.
-#define TRACE_EVENT_BEGIN0(category, name) \
-    INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_BEGIN, \
-        category, name, TRACE_EVENT_FLAG_NONE)
-#define TRACE_EVENT_BEGIN1(category, name, arg1_name, arg1_val) \
-    INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_BEGIN, \
-        category, name, TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val)
-#define TRACE_EVENT_BEGIN2(category, name, arg1_name, arg1_val, \
-        arg2_name, arg2_val) \
-    INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_BEGIN, \
-        category, name, TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val, \
-        arg2_name, arg2_val)
-#define TRACE_EVENT_COPY_BEGIN0(category, name) \
-    INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_BEGIN, \
-        category, name, TRACE_EVENT_FLAG_COPY)
-#define TRACE_EVENT_COPY_BEGIN1(category, name, arg1_name, arg1_val) \
-    INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_BEGIN, \
-        category, name, TRACE_EVENT_FLAG_COPY, arg1_name, arg1_val)
-#define TRACE_EVENT_COPY_BEGIN2(category, name, arg1_name, arg1_val, \
-        arg2_name, arg2_val) \
-    INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_BEGIN, \
-        category, name, TRACE_EVENT_FLAG_COPY, arg1_name, arg1_val, \
-        arg2_name, arg2_val)
-
-// Records a single END event for "name" immediately. If the category
-// is not enabled, then this does nothing.
-// - category and name strings must have application lifetime (statics or
-//   literals). They may not include " chars.
-#define TRACE_EVENT_END0(category, name) \
-    INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_END, \
-        category, name, TRACE_EVENT_FLAG_NONE)
-#define TRACE_EVENT_END1(category, name, arg1_name, arg1_val) \
-    INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_END, \
-        category, name, TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val)
-#define TRACE_EVENT_END2(category, name, arg1_name, arg1_val, \
-        arg2_name, arg2_val) \
-    INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_END, \
-        category, name, TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val, \
-        arg2_name, arg2_val)
-#define TRACE_EVENT_COPY_END0(category, name) \
-    INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_END, \
-        category, name, TRACE_EVENT_FLAG_COPY)
-#define TRACE_EVENT_COPY_END1(category, name, arg1_name, arg1_val) \
-    INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_END, \
-        category, name, TRACE_EVENT_FLAG_COPY, arg1_name, arg1_val)
-#define TRACE_EVENT_COPY_END2(category, name, arg1_name, arg1_val, \
-        arg2_name, arg2_val) \
-    INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_END, \
-        category, name, TRACE_EVENT_FLAG_COPY, arg1_name, arg1_val, \
-        arg2_name, arg2_val)
-
-// Records the value of a counter called "name" immediately. Value
-// must be representable as a 32 bit integer.
-// - category and name strings must have application lifetime (statics or
-//   literals). They may not include " chars.
-#define TRACE_COUNTER1(category, name, value) \
-    INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_COUNTER, \
-        category, name, TRACE_EVENT_FLAG_NONE, \
-        "value", static_cast<int>(value))
-#define TRACE_COPY_COUNTER1(category, name, value) \
-    INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_COUNTER, \
-        category, name, TRACE_EVENT_FLAG_COPY, \
-        "value", static_cast<int>(value))
-
-// Records the values of a multi-parted counter called "name" immediately.
-// The UI will treat value1 and value2 as parts of a whole, displaying their
-// values as a stacked-bar chart.
-// - category and name strings must have application lifetime (statics or
-//   literals). They may not include " chars.
-#define TRACE_COUNTER2(category, name, value1_name, value1_val, \
-        value2_name, value2_val) \
-    INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_COUNTER, \
-        category, name, TRACE_EVENT_FLAG_NONE, \
-        value1_name, static_cast<int>(value1_val), \
-        value2_name, static_cast<int>(value2_val))
-#define TRACE_COPY_COUNTER2(category, name, value1_name, value1_val, \
-        value2_name, value2_val) \
-    INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_COUNTER, \
-        category, name, TRACE_EVENT_FLAG_COPY, \
-        value1_name, static_cast<int>(value1_val), \
-        value2_name, static_cast<int>(value2_val))
-
-// Records the value of a counter called "name" immediately. Value
-// must be representable as a 32 bit integer.
-// - category and name strings must have application lifetime (statics or
-//   literals). They may not include " chars.
-// - |id| is used to disambiguate counters with the same name. It must either
-//   be a pointer or an integer value up to 64 bits. If it's a pointer, the bits
-//   will be xored with a hash of the process ID so that the same pointer on
-//   two different processes will not collide.
-#define TRACE_COUNTER_ID1(category, name, id, value) \
-    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_COUNTER, \
-        category, name, id, TRACE_EVENT_FLAG_NONE, \
-        "value", static_cast<int>(value))
-#define TRACE_COPY_COUNTER_ID1(category, name, id, value) \
-    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_COUNTER, \
-        category, name, id, TRACE_EVENT_FLAG_COPY, \
-        "value", static_cast<int>(value))
-
-// Records the values of a multi-parted counter called "name" immediately.
-// The UI will treat value1 and value2 as parts of a whole, displaying their
-// values as a stacked-bar chart.
-// - category and name strings must have application lifetime (statics or
-//   literals). They may not include " chars.
-// - |id| is used to disambiguate counters with the same name. It must either
-//   be a pointer or an integer value up to 64 bits. If it's a pointer, the bits
-//   will be xored with a hash of the process ID so that the same pointer on
-//   two different processes will not collide.
-#define TRACE_COUNTER_ID2(category, name, id, value1_name, value1_val, \
-        value2_name, value2_val) \
-    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_COUNTER, \
-        category, name, id, TRACE_EVENT_FLAG_NONE, \
-        value1_name, static_cast<int>(value1_val), \
-        value2_name, static_cast<int>(value2_val))
-#define TRACE_COPY_COUNTER_ID2(category, name, id, value1_name, value1_val, \
-        value2_name, value2_val) \
-    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_COUNTER, \
-        category, name, id, TRACE_EVENT_FLAG_COPY, \
-        value1_name, static_cast<int>(value1_val), \
-        value2_name, static_cast<int>(value2_val))
-
-// Records a single ASYNC_BEGIN event called "name" immediately, with 0, 1 or 2
-// associated arguments. If the category is not enabled, then this
-// does nothing.
-// - category and name strings must have application lifetime (statics or
-//   literals). They may not include " chars.
-// - |id| is used to match the ASYNC_BEGIN event with the ASYNC_END event. ASYNC
-//   events are considered to match if their category, name and id values all
-//   match. |id| must either be a pointer or an integer value up to 64 bits. If
-//   it's a pointer, the bits will be xored with a hash of the process ID so
-//   that the same pointer on two different processes will not collide.
-//
-// An asynchronous operation can consist of multiple phases. The first phase is
-// defined by the ASYNC_BEGIN calls. Additional phases can be defined using the
-// ASYNC_STEP_INTO or ASYNC_STEP_PAST macros. The ASYNC_STEP_INTO macro will
-// annotate the block following the call. The ASYNC_STEP_PAST macro will
-// annotate the block prior to the call. Note that any particular event must use
-// only STEP_INTO or STEP_PAST macros; they can not mix and match. When the
-// operation completes, call ASYNC_END.
-//
-// An ASYNC trace typically occurs on a single thread (if not, they will only be
-// drawn on the thread defined in the ASYNC_BEGIN event), but all events in that
-// operation must use the same |name| and |id|. Each step can have its own
-#define TRACE_EVENT_ASYNC_BEGIN0(category, name, id) \
-    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_BEGIN, \
-        category, name, id, TRACE_EVENT_FLAG_NONE)
-#define TRACE_EVENT_ASYNC_BEGIN1(category, name, id, arg1_name, arg1_val) \
-    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_BEGIN, \
-        category, name, id, TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val)
-#define TRACE_EVENT_ASYNC_BEGIN2(category, name, id, arg1_name, arg1_val, \
-        arg2_name, arg2_val) \
-    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_BEGIN, \
-        category, name, id, TRACE_EVENT_FLAG_NONE, \
-        arg1_name, arg1_val, arg2_name, arg2_val)
-#define TRACE_EVENT_COPY_ASYNC_BEGIN0(category, name, id) \
-    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_BEGIN, \
-        category, name, id, TRACE_EVENT_FLAG_COPY)
-#define TRACE_EVENT_COPY_ASYNC_BEGIN1(category, name, id, arg1_name, arg1_val) \
-    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_BEGIN, \
-        category, name, id, TRACE_EVENT_FLAG_COPY, \
-        arg1_name, arg1_val)
-#define TRACE_EVENT_COPY_ASYNC_BEGIN2(category, name, id, arg1_name, arg1_val, \
-        arg2_name, arg2_val) \
-    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_BEGIN, \
-        category, name, id, TRACE_EVENT_FLAG_COPY, \
-        arg1_name, arg1_val, arg2_name, arg2_val)
-
-// Records a single ASYNC_STEP_INTO event for |step| immediately. If the
-// category is not enabled, then this does nothing. The |name| and |id| must
-// match the ASYNC_BEGIN event above. The |step| param identifies this step
-// within the async event. This should be called at the beginning of the next
-// phase of an asynchronous operation. The ASYNC_BEGIN event must not have any
-// ASYNC_STEP_PAST events.
-#define TRACE_EVENT_ASYNC_STEP_INTO0(category, name, id, step) \
-    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_STEP_INTO, \
-        category, name, id, TRACE_EVENT_FLAG_NONE, "step", step)
-#define TRACE_EVENT_ASYNC_STEP_INTO1(category, name, id, step, \
-        arg1_name, arg1_val) \
-    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_STEP_INTO, \
-        category, name, id, TRACE_EVENT_FLAG_NONE, "step", step, \
-        arg1_name, arg1_val)
-
-// Records a single ASYNC_STEP_PAST event for |step| immediately. If the
-// category is not enabled, then this does nothing. The |name| and |id| must
-// match the ASYNC_BEGIN event above. The |step| param identifies this step
-// within the async event. This should be called at the beginning of the next
-// phase of an asynchronous operation. The ASYNC_BEGIN event must not have any
-// ASYNC_STEP_INTO events.
-#define TRACE_EVENT_ASYNC_STEP_PAST0(category_group, name, id, step) \
-    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_STEP_PAST, \
-        category_group, name, id, TRACE_EVENT_FLAG_NONE, "step", step)
-#define TRACE_EVENT_ASYNC_STEP_PAST1(category_group, name, id, step, arg1_name, arg1_val) \
-    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_STEP_PAST, \
-        category_group, name, id, TRACE_EVENT_FLAG_NONE, "step", step, \
-        arg1_name, arg1_val)
-
-// Records a single ASYNC_END event for "name" immediately. If the category
-// is not enabled, then this does nothing.
-#define TRACE_EVENT_ASYNC_END0(category, name, id) \
-    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_END, \
-        category, name, id, TRACE_EVENT_FLAG_NONE)
-#define TRACE_EVENT_ASYNC_END1(category, name, id, arg1_name, arg1_val) \
-    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_END, \
-        category, name, id, TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val)
-#define TRACE_EVENT_ASYNC_END2(category, name, id, arg1_name, arg1_val, \
-        arg2_name, arg2_val) \
-    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_END, \
-        category, name, id, TRACE_EVENT_FLAG_NONE, \
-        arg1_name, arg1_val, arg2_name, arg2_val)
-#define TRACE_EVENT_COPY_ASYNC_END0(category, name, id) \
-    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_END, \
-        category, name, id, TRACE_EVENT_FLAG_COPY)
-#define TRACE_EVENT_COPY_ASYNC_END1(category, name, id, arg1_name, arg1_val) \
-    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_END, \
-        category, name, id, TRACE_EVENT_FLAG_COPY, \
-        arg1_name, arg1_val)
-#define TRACE_EVENT_COPY_ASYNC_END2(category, name, id, arg1_name, arg1_val, \
-        arg2_name, arg2_val) \
-    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_END, \
-        category, name, id, TRACE_EVENT_FLAG_COPY, \
-        arg1_name, arg1_val, arg2_name, arg2_val)
-
-// Creates a scope of a sampling state with the given category and name (both must
-// be constant strings). These states are intended for a sampling profiler.
-// Implementation note: we store category and name together because we don't
-// want the inconsistency/expense of storing two pointers.
-// |thread_bucket| is [0..2] and is used to statically isolate samples in one
-// thread from others.
-//
-// {  // The sampling state is set within this scope.
-//    TRACE_EVENT_SAMPLING_STATE_SCOPE_FOR_BUCKET(0, "category", "name");
-//    ...;
-// }
-#define TRACE_EVENT_SCOPED_SAMPLING_STATE_FOR_BUCKET(bucket_number, category, name) \
-    TraceEvent::SamplingStateScope<bucket_number> traceEventSamplingScope(category "\0" name);
-
-// Returns a current sampling state of the given bucket.
-// The format of the returned string is "category\0name".
-#define TRACE_EVENT_GET_SAMPLING_STATE_FOR_BUCKET(bucket_number) \
-    TraceEvent::SamplingStateScope<bucket_number>::current()
-
-// Sets a current sampling state of the given bucket.
-// |category| and |name| have to be constant strings.
-#define TRACE_EVENT_SET_SAMPLING_STATE_FOR_BUCKET(bucket_number, category, name) \
-    TraceEvent::SamplingStateScope<bucket_number>::set(category "\0" name)
-
-// Sets a current sampling state of the given bucket.
-// |categoryAndName| doesn't need to be a constant string.
-// The format of the string is "category\0name".
-#define TRACE_EVENT_SET_NONCONST_SAMPLING_STATE_FOR_BUCKET(bucket_number, categoryAndName) \
-    TraceEvent::SamplingStateScope<bucket_number>::set(categoryAndName)
-
-// Syntactic sugars for the sampling tracing in the main thread.
-#define TRACE_EVENT_SCOPED_SAMPLING_STATE(category, name) \
-    TRACE_EVENT_SCOPED_SAMPLING_STATE_FOR_BUCKET(0, category, name)
-#define TRACE_EVENT_GET_SAMPLING_STATE() \
-    TRACE_EVENT_GET_SAMPLING_STATE_FOR_BUCKET(0)
-#define TRACE_EVENT_SET_SAMPLING_STATE(category, name) \
-    TRACE_EVENT_SET_SAMPLING_STATE_FOR_BUCKET(0, category, name)
-#define TRACE_EVENT_SET_NONCONST_SAMPLING_STATE(categoryAndName) \
-    TRACE_EVENT_SET_NONCONST_SAMPLING_STATE_FOR_BUCKET(0, categoryAndName)
-
-// Macros to track the life time and value of arbitrary client objects.
-// See also TraceTrackableObject.
-#define TRACE_EVENT_OBJECT_CREATED_WITH_ID(categoryGroup, name, id) \
-    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_CREATE_OBJECT, \
-        categoryGroup, name, TRACE_ID_DONT_MANGLE(id), TRACE_EVENT_FLAG_NONE)
-
-#define TRACE_EVENT_OBJECT_DELETED_WITH_ID(categoryGroup, name, id) \
-    INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_DELETE_OBJECT, \
-        categoryGroup, name, TRACE_ID_DONT_MANGLE(id), TRACE_EVENT_FLAG_NONE)
-
-// Macro to efficiently determine if a given category group is enabled.
-#define TRACE_EVENT_CATEGORY_GROUP_ENABLED(categoryGroup, ret) \
-    do { \
-        INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(categoryGroup);  \
-        if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE()) { \
-            *ret = true;                                        \
-        } else {                                                \
-            *ret = false;                                       \
-        }                                                       \
-    } while (0)
-
-// This will mark the trace event as disabled by default. The user will need
-// to explicitly enable the event.
-#define TRACE_DISABLED_BY_DEFAULT(name) "disabled-by-default-" name
-
-////////////////////////////////////////////////////////////////////////////////
-// Implementation specific tracing API definitions.
-
-// Get a pointer to the enabled state of the given trace category. Only
-// long-lived literal strings should be given as the category name. The returned
-// pointer can be held permanently in a local static for example. If the
-// unsigned char is non-zero, tracing is enabled. If tracing is enabled,
-// TRACE_EVENT_API_ADD_TRACE_EVENT can be called. It's OK if tracing is disabled
-// between the load of the tracing state and the call to
-// TRACE_EVENT_API_ADD_TRACE_EVENT, because this flag only provides an early out
-// for best performance when tracing is disabled.
-// const unsigned char*
-//     TRACE_EVENT_API_GET_CATEGORY_ENABLED(const char* category_name)
-#define TRACE_EVENT_API_GET_CATEGORY_ENABLED \
-    WebCore::EventTracer::getTraceCategoryEnabledFlag
-
-// Add a trace event to the platform tracing system.
-// WebCore::TraceEvent::TraceEventHandle TRACE_EVENT_API_ADD_TRACE_EVENT(
-//                    char phase,
-//                    const unsigned char* category_enabled,
-//                    const char* name,
-//                    unsigned long long id,
-//                    int num_args,
-//                    const char** arg_names,
-//                    const unsigned char* arg_types,
-//                    const unsigned long long* arg_values,
-//                    unsigned char flags)
-#define TRACE_EVENT_API_ADD_TRACE_EVENT \
-    WebCore::EventTracer::addTraceEvent
-
-// Set the duration field of a COMPLETE trace event.
-// void TRACE_EVENT_API_UPDATE_TRACE_EVENT_DURATION(
-//     WebCore::TraceEvent::TraceEventHandle handle)
-#define TRACE_EVENT_API_UPDATE_TRACE_EVENT_DURATION \
-    WebCore::EventTracer::updateTraceEventDuration
-
-////////////////////////////////////////////////////////////////////////////////
-
-// Implementation detail: trace event macros create temporary variables
-// to keep instrumentation overhead low. These macros give each temporary
-// variable a unique name based on the line number to prevent name collissions.
-#define INTERNAL_TRACE_EVENT_UID3(a, b) \
-    trace_event_unique_##a##b
-#define INTERNAL_TRACE_EVENT_UID2(a, b) \
-    INTERNAL_TRACE_EVENT_UID3(a, b)
-#define INTERNALTRACEEVENTUID(name_prefix) \
-    INTERNAL_TRACE_EVENT_UID2(name_prefix, __LINE__)
-
-// Implementation detail: internal macro to create static category.
-// - WTF_ANNOTATE_BENIGN_RACE, see Thread Safety above.
-
-#define INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category) \
-    static const unsigned char* INTERNALTRACEEVENTUID(categoryGroupEnabled) = 0; \
-    WTF_ANNOTATE_BENIGN_RACE(&INTERNALTRACEEVENTUID(categoryGroupEnabled), \
-                             "trace_event category"); \
-    if (!INTERNALTRACEEVENTUID(categoryGroupEnabled)) { \
-        INTERNALTRACEEVENTUID(categoryGroupEnabled) = \
-            TRACE_EVENT_API_GET_CATEGORY_ENABLED(category); \
-    }
-
-// Implementation detail: internal macro to create static category and add
-// event if the category is enabled.
-#define INTERNAL_TRACE_EVENT_ADD(phase, category, name, flags, ...) \
-    do { \
-        INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category); \
-        if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE()) { \
-            WebCore::TraceEvent::addTraceEvent( \
-                phase, INTERNALTRACEEVENTUID(categoryGroupEnabled), name, \
-                WebCore::TraceEvent::noEventId, flags, ##__VA_ARGS__); \
-        } \
-    } while (0)
-
-// Implementation detail: internal macro to create static category and add begin
-// event if the category is enabled. Also adds the end event when the scope
-// ends.
-#define INTERNAL_TRACE_EVENT_ADD_SCOPED(category, name, ...) \
-    INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category); \
-    WebCore::TraceEvent::ScopedTracer INTERNALTRACEEVENTUID(scopedTracer); \
-    if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE()) { \
-        WebCore::TraceEvent::TraceEventHandle h = \
-            WebCore::TraceEvent::addTraceEvent( \
-                TRACE_EVENT_PHASE_COMPLETE, \
-                INTERNALTRACEEVENTUID(categoryGroupEnabled), \
-                name, WebCore::TraceEvent::noEventId, \
-                TRACE_EVENT_FLAG_NONE, ##__VA_ARGS__); \
-        INTERNALTRACEEVENTUID(scopedTracer).initialize( \
-            INTERNALTRACEEVENTUID(categoryGroupEnabled), name, h); \
-    }
-
-// Implementation detail: internal macro to create static category and add
-// event if the category is enabled.
-#define INTERNAL_TRACE_EVENT_ADD_WITH_ID(phase, category, name, id, flags, \
-                                         ...) \
-    do { \
-        INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category); \
-        if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE()) { \
-            unsigned char traceEventFlags = flags | TRACE_EVENT_FLAG_HAS_ID; \
-            WebCore::TraceEvent::TraceID traceEventTraceID( \
-                id, &traceEventFlags); \
-            WebCore::TraceEvent::addTraceEvent( \
-                phase, INTERNALTRACEEVENTUID(categoryGroupEnabled), \
-                name, traceEventTraceID.data(), traceEventFlags, \
-                ##__VA_ARGS__); \
-        } \
-    } while (0)
-
-// Notes regarding the following definitions:
-// New values can be added and propagated to third party libraries, but existing
-// definitions must never be changed, because third party libraries may use old
-// definitions.
-
-// Phase indicates the nature of an event entry. E.g. part of a begin/end pair.
-#define TRACE_EVENT_PHASE_BEGIN    ('B')
-#define TRACE_EVENT_PHASE_END      ('E')
-#define TRACE_EVENT_PHASE_COMPLETE ('X')
-// FIXME: unify instant events handling between blink and platform.
-#define TRACE_EVENT_PHASE_INSTANT  ('I')
-#define TRACE_EVENT_PHASE_INSTANT_WITH_SCOPE  ('i')
-#define TRACE_EVENT_PHASE_ASYNC_BEGIN ('S')
-#define TRACE_EVENT_PHASE_ASYNC_STEP_INTO  ('T')
-#define TRACE_EVENT_PHASE_ASYNC_STEP_PAST  ('p')
-#define TRACE_EVENT_PHASE_ASYNC_END   ('F')
-#define TRACE_EVENT_PHASE_METADATA ('M')
-#define TRACE_EVENT_PHASE_COUNTER  ('C')
-#define TRACE_EVENT_PHASE_SAMPLE  ('P')
-#define TRACE_EVENT_PHASE_CREATE_OBJECT ('N')
-#define TRACE_EVENT_PHASE_DELETE_OBJECT ('D')
-
-// Flags for changing the behavior of TRACE_EVENT_API_ADD_TRACE_EVENT.
-#define TRACE_EVENT_FLAG_NONE        (static_cast<unsigned char>(0))
-#define TRACE_EVENT_FLAG_COPY        (static_cast<unsigned char>(1 << 0))
-#define TRACE_EVENT_FLAG_HAS_ID      (static_cast<unsigned char>(1 << 1))
-#define TRACE_EVENT_FLAG_MANGLE_ID   (static_cast<unsigned char>(1 << 2))
-
-// Type values for identifying types in the TraceValue union.
-#define TRACE_VALUE_TYPE_BOOL         (static_cast<unsigned char>(1))
-#define TRACE_VALUE_TYPE_UINT         (static_cast<unsigned char>(2))
-#define TRACE_VALUE_TYPE_INT          (static_cast<unsigned char>(3))
-#define TRACE_VALUE_TYPE_DOUBLE       (static_cast<unsigned char>(4))
-#define TRACE_VALUE_TYPE_POINTER      (static_cast<unsigned char>(5))
-#define TRACE_VALUE_TYPE_STRING       (static_cast<unsigned char>(6))
-#define TRACE_VALUE_TYPE_COPY_STRING  (static_cast<unsigned char>(7))
-
-// These values must be in sync with base::debug::TraceLog::CategoryGroupEnabledFlags.
-#define ENABLED_FOR_RECORDING (1 << 0)
-#define ENABLED_FOR_EVENT_CALLBACK (1 << 2)
-
-#define INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE() \
-    (*INTERNALTRACEEVENTUID(categoryGroupEnabled) & (ENABLED_FOR_RECORDING | ENABLED_FOR_EVENT_CALLBACK))
-
-namespace WebCore {
-
-namespace TraceEvent {
-
-// Specify these values when the corresponding argument of addTraceEvent is not
-// used.
-const int zeroNumArgs = 0;
-const unsigned long long noEventId = 0;
-
-// TraceID encapsulates an ID that can either be an integer or pointer. Pointers
-// are mangled with the Process ID so that they are unlikely to collide when the
-// same pointer is used on different processes.
-class TraceID {
-public:
-    template<bool dummyMangle> class MangleBehavior {
-    public:
-        template<typename T> explicit MangleBehavior(T id) : m_data(reinterpret_cast<unsigned long long>(id)) { }
-        unsigned long long data() const { return m_data; }
-    private:
-        unsigned long long m_data;
-    };
-    typedef MangleBehavior<false> DontMangle;
-    typedef MangleBehavior<true> ForceMangle;
-
-    TraceID(const void* id, unsigned char* flags) :
-        m_data(static_cast<unsigned long long>(reinterpret_cast<unsigned long>(id)))
-    {
-        *flags |= TRACE_EVENT_FLAG_MANGLE_ID;
-    }
-    TraceID(ForceMangle id, unsigned char* flags) : m_data(id.data())
-    {
-        *flags |= TRACE_EVENT_FLAG_MANGLE_ID;
-    }
-    TraceID(DontMangle id, unsigned char*) : m_data(id.data()) { }
-    TraceID(unsigned long long id, unsigned char*) : m_data(id) { }
-    TraceID(unsigned long id, unsigned char*) : m_data(id) { }
-    TraceID(unsigned id, unsigned char*) : m_data(id) { }
-    TraceID(unsigned short id, unsigned char*) : m_data(id) { }
-    TraceID(unsigned char id, unsigned char*) : m_data(id) { }
-    TraceID(long long id, unsigned char*) :
-        m_data(static_cast<unsigned long long>(id)) { }
-    TraceID(long id, unsigned char*) :
-        m_data(static_cast<unsigned long long>(id)) { }
-    TraceID(int id, unsigned char*) :
-        m_data(static_cast<unsigned long long>(id)) { }
-    TraceID(short id, unsigned char*) :
-        m_data(static_cast<unsigned long long>(id)) { }
-    TraceID(signed char id, unsigned char*) :
-        m_data(static_cast<unsigned long long>(id)) { }
-
-    unsigned long long data() const { return m_data; }
-
-private:
-    unsigned long long m_data;
-};
-
-// Simple union to store various types as unsigned long long.
-union TraceValueUnion {
-    bool m_bool;
-    unsigned long long m_uint;
-    long long m_int;
-    double m_double;
-    const void* m_pointer;
-    const char* m_string;
-};
-
-// Simple container for const char* that should be copied instead of retained.
-class TraceStringWithCopy {
-public:
-    explicit TraceStringWithCopy(const char* str) : m_str(str) { }
-    operator const char* () const { return m_str; }
-private:
-    const char* m_str;
-};
-
-// Define setTraceValue for each allowed type. It stores the type and
-// value in the return arguments. This allows this API to avoid declaring any
-// structures so that it is portable to third_party libraries.
-#define INTERNAL_DECLARE_SET_TRACE_VALUE(actual_type, \
-                                         union_member, \
-                                         value_type_id) \
-    static inline void setTraceValue(actual_type arg, \
-                                     unsigned char* type, \
-                                     unsigned long long* value) { \
-        TraceValueUnion typeValue; \
-        typeValue.union_member = arg; \
-        *type = value_type_id; \
-        *value = typeValue.m_uint; \
-    }
-// Simpler form for int types that can be safely casted.
-#define INTERNAL_DECLARE_SET_TRACE_VALUE_INT(actual_type, \
-                                             value_type_id) \
-    static inline void setTraceValue(actual_type arg, \
-                                     unsigned char* type, \
-                                     unsigned long long* value) { \
-        *type = value_type_id; \
-        *value = static_cast<unsigned long long>(arg); \
-    }
-
-INTERNAL_DECLARE_SET_TRACE_VALUE_INT(unsigned long long, TRACE_VALUE_TYPE_UINT)
-INTERNAL_DECLARE_SET_TRACE_VALUE_INT(unsigned int, TRACE_VALUE_TYPE_UINT)
-INTERNAL_DECLARE_SET_TRACE_VALUE_INT(unsigned short, TRACE_VALUE_TYPE_UINT)
-INTERNAL_DECLARE_SET_TRACE_VALUE_INT(unsigned char, TRACE_VALUE_TYPE_UINT)
-INTERNAL_DECLARE_SET_TRACE_VALUE_INT(long long, TRACE_VALUE_TYPE_INT)
-INTERNAL_DECLARE_SET_TRACE_VALUE_INT(int, TRACE_VALUE_TYPE_INT)
-INTERNAL_DECLARE_SET_TRACE_VALUE_INT(short, TRACE_VALUE_TYPE_INT)
-INTERNAL_DECLARE_SET_TRACE_VALUE_INT(signed char, TRACE_VALUE_TYPE_INT)
-INTERNAL_DECLARE_SET_TRACE_VALUE(bool, m_bool, TRACE_VALUE_TYPE_BOOL)
-INTERNAL_DECLARE_SET_TRACE_VALUE(double, m_double, TRACE_VALUE_TYPE_DOUBLE)
-INTERNAL_DECLARE_SET_TRACE_VALUE(const void*, m_pointer,
-                                 TRACE_VALUE_TYPE_POINTER)
-INTERNAL_DECLARE_SET_TRACE_VALUE(const char*, m_string,
-                                 TRACE_VALUE_TYPE_STRING)
-INTERNAL_DECLARE_SET_TRACE_VALUE(const TraceStringWithCopy&, m_string,
-                                 TRACE_VALUE_TYPE_COPY_STRING)
-
-#undef INTERNAL_DECLARE_SET_TRACE_VALUE
-#undef INTERNAL_DECLARE_SET_TRACE_VALUE_INT
-
-// WTF::String version of setTraceValue so that trace arguments can be strings.
-static inline void setTraceValue(const WTF::CString& arg, unsigned char* type, unsigned long long* value)
-{
-    TraceValueUnion typeValue;
-    typeValue.m_string = arg.data();
-    *type = TRACE_VALUE_TYPE_COPY_STRING;
-    *value = typeValue.m_uint;
-}
-
-// These addTraceEvent template functions are defined here instead of in the
-// macro, because the arg values could be temporary string objects. In order to
-// store pointers to the internal c_str and pass through to the tracing API, the
-// arg values must live throughout these procedures.
-
-static inline TraceEventHandle addTraceEvent(
-    char phase,
-    const unsigned char* categoryEnabled,
-    const char* name,
-    unsigned long long id,
-    unsigned char flags)
-{
-    return TRACE_EVENT_API_ADD_TRACE_EVENT(
-        phase, categoryEnabled, name, id,
-        zeroNumArgs, 0, 0, 0,
-        flags);
-}
-
-template<class ARG1_TYPE>
-static inline TraceEventHandle addTraceEvent(
-    char phase,
-    const unsigned char* categoryEnabled,
-    const char* name,
-    unsigned long long id,
-    unsigned char flags,
-    const char* arg1Name,
-    const ARG1_TYPE& arg1Val)
-{
-    const int numArgs = 1;
-    unsigned char argTypes[1];
-    unsigned long long argValues[1];
-    setTraceValue(arg1Val, &argTypes[0], &argValues[0]);
-    return TRACE_EVENT_API_ADD_TRACE_EVENT(
-        phase, categoryEnabled, name, id,
-        numArgs, &arg1Name, argTypes, argValues,
-        flags);
-}
-
-template<class ARG1_TYPE, class ARG2_TYPE>
-static inline TraceEventHandle addTraceEvent(
-    char phase,
-    const unsigned char* categoryEnabled,
-    const char* name,
-    unsigned long long id,
-    unsigned char flags,
-    const char* arg1Name,
-    const ARG1_TYPE& arg1Val,
-    const char* arg2Name,
-    const ARG2_TYPE& arg2Val)
-{
-    const int numArgs = 2;
-    const char* argNames[2] = { arg1Name, arg2Name };
-    unsigned char argTypes[2];
-    unsigned long long argValues[2];
-    setTraceValue(arg1Val, &argTypes[0], &argValues[0]);
-    setTraceValue(arg2Val, &argTypes[1], &argValues[1]);
-    return TRACE_EVENT_API_ADD_TRACE_EVENT(
-        phase, categoryEnabled, name, id,
-        numArgs, argNames, argTypes, argValues,
-        flags);
-}
-
-// Used by TRACE_EVENTx macro. Do not use directly.
-class ScopedTracer {
-public:
-    // Note: members of m_data intentionally left uninitialized. See initialize.
-    ScopedTracer() : m_pdata(0) { }
-    ~ScopedTracer()
-    {
-        if (m_pdata && *m_pdata->categoryGroupEnabled)
-            TRACE_EVENT_API_UPDATE_TRACE_EVENT_DURATION(m_data.categoryGroupEnabled, m_data.name, m_data.eventHandle);
-    }
-
-    void initialize(const unsigned char* categoryGroupEnabled, const char* name, TraceEventHandle eventHandle)
-    {
-        m_data.categoryGroupEnabled = categoryGroupEnabled;
-        m_data.name = name;
-        m_data.eventHandle = eventHandle;
-        m_pdata = &m_data;
-    }
-
-private:
-    // This Data struct workaround is to avoid initializing all the members
-    // in Data during construction of this object, since this object is always
-    // constructed, even when tracing is disabled. If the members of Data were
-    // members of this class instead, compiler warnings occur about potential
-    // uninitialized accesses.
-    struct Data {
-        const unsigned char* categoryGroupEnabled;
-        const char* name;
-        TraceEventHandle eventHandle;
-    };
-    Data* m_pdata;
-    Data m_data;
-};
-
-// TraceEventSamplingStateScope records the current sampling state
-// and sets a new sampling state. When the scope exists, it restores
-// the sampling state having recorded.
-template<size_t BucketNumber>
-class SamplingStateScope {
-    WTF_MAKE_FAST_ALLOCATED;
-public:
-    SamplingStateScope(const char* categoryAndName)
-    {
-        m_previousState = SamplingStateScope<BucketNumber>::current();
-        SamplingStateScope<BucketNumber>::set(categoryAndName);
-    }
-
-    ~SamplingStateScope()
-    {
-        SamplingStateScope<BucketNumber>::set(m_previousState);
-    }
-
-    // FIXME: Make load/store to traceSamplingState[] thread-safe and atomic.
-    static inline const char* current()
-    {
-        return reinterpret_cast<const char*>(*WebCore::traceSamplingState[BucketNumber]);
-    }
-    static inline void set(const char* categoryAndName)
-    {
-        *WebCore::traceSamplingState[BucketNumber] = reinterpret_cast<long>(const_cast<char*>(categoryAndName));
-    }
-
-private:
-    const char* m_previousState;
-};
-
-template<typename IDType> class TraceScopedTrackableObject {
-    WTF_MAKE_NONCOPYABLE(TraceScopedTrackableObject);
-public:
-    TraceScopedTrackableObject(const char* categoryGroup, const char* name, IDType id)
-        : m_categoryGroup(categoryGroup), m_name(name), m_id(id)
-    {
-        TRACE_EVENT_OBJECT_CREATED_WITH_ID(m_categoryGroup, m_name, m_id);
-    }
-
-    ~TraceScopedTrackableObject()
-    {
-        TRACE_EVENT_OBJECT_DELETED_WITH_ID(m_categoryGroup, m_name, m_id);
-    }
-
-private:
-    const char* m_categoryGroup;
-    const char* m_name;
-    IDType m_id;
-};
-
-} // namespace TraceEvent
-
-} // namespace WebCore
-
-#endif