Moved the cross-project parts of trace_event.h to trace_event_common.h

base/trace_event/trace_event_common.h

Index: base/trace_event/trace_event_common.h
diff --git a/base/trace_event/trace_event_common.h b/base/trace_event/trace_event_common.h
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+++ b/base/trace_event/trace_event_common.h
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+// 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.
+
+// This header file defines the set of trace_event macros without specifying
+// how the events actually get collected and stored. If you need to expose trace
+// events to some other universe, you can copy-and-paste this file as well as
+// trace_event.h, modifying the macros contained there as necessary for the
+// target platform. The end result is that multiple libraries can funnel events
+// through to a shared trace event collector.
+
+// IMPORTANT: To avoid conflicts, if you need to modify this file for a library,
+// land your change in base/ first, and then copy-and-paste it.
+
+// 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",
+//                        TRACE_EVENT_SCOPE_THREAD)
+//
+// It is often the case that one trace may belong in multiple categories at the
+// same time. The first argument to the trace can be a comma-separated list of
+// categories, forming a category group, like:
+//
+// TRACE_EVENT_INSTANT0("input,views", "OnMouseOver", TRACE_EVENT_SCOPE_THREAD)
+//
+// We can enable/disable tracing of OnMouseOver by enabling/disabling either
+// category.
+//
+// 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 disambiguate 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_group, name, and arg_names.  Thus, the following code will
+// cause problems:
+//     char* str = strdup("importantName");
+//     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"));
+//
+//
+// Convertable notes:
+// Converting a large data type to a string can be costly. To help with this,
+// the trace framework provides an interface ConvertableToTraceFormat. If you
+// inherit from it and implement the AppendAsTraceFormat method the trace
+// framework will call back to your object to convert a trace output time. This
+// means, if the category for the event is disabled, the conversion will not
+// happen.
+//
+//   class MyData : public base::trace_event::ConvertableToTraceFormat {
+//    public:
+//     MyData() {}
+//     void AppendAsTraceFormat(std::string* out) const override {
+//       out->append("{\"foo\":1}");
+//     }
+//    private:
+//     ~MyData() override {}
+//     DISALLOW_COPY_AND_ASSIGN(MyData);
+//   };
+//
+//   TRACE_EVENT1("foo", "bar", "data",
+//                scoped_refptr<ConvertableToTraceFormat>(new MyData()));
+//
+// The trace framework will take ownership if the passed pointer and it will
+// be free'd when the trace buffer is flushed.
+//
+// Note, we only do the conversion when the buffer is flushed, so the provided
+// data object should not be modified after it's passed to the trace framework.
+//
+//
+// 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_group_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 acquiring a lock
+// and resolving the category.
+
+#if defined(TRACE_EVENT0)
+#error "Another copy of this file has already been included."
+#endif
+
+// 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
+
+// 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_group, name)    \
+  INTERNAL_TRACE_MEMORY(category_group, name) \
+  INTERNAL_TRACE_EVENT_ADD_SCOPED(category_group, name)
+#define TRACE_EVENT_WITH_FLOW0(category_group, name, bind_id, flow_flags)  \
+  INTERNAL_TRACE_MEMORY(category_group, name)                              \
+  INTERNAL_TRACE_EVENT_ADD_SCOPED_WITH_FLOW(category_group, name, bind_id, \
+                                            flow_flags)
+#define TRACE_EVENT1(category_group, name, arg1_name, arg1_val) \
+  INTERNAL_TRACE_MEMORY(category_group, name)                   \
+  INTERNAL_TRACE_EVENT_ADD_SCOPED(category_group, name, arg1_name, arg1_val)
+#define TRACE_EVENT_WITH_FLOW1(category_group, name, bind_id, flow_flags,  \
+                               arg1_name, arg1_val)                        \
+  INTERNAL_TRACE_MEMORY(category_group, name)                              \
+  INTERNAL_TRACE_EVENT_ADD_SCOPED_WITH_FLOW(category_group, name, bind_id, \
+                                            flow_flags, arg1_name, arg1_val)
+#define TRACE_EVENT2(category_group, name, arg1_name, arg1_val, arg2_name,   \
+                     arg2_val)                                               \
+  INTERNAL_TRACE_MEMORY(category_group, name)                                \
+  INTERNAL_TRACE_EVENT_ADD_SCOPED(category_group, name, arg1_name, arg1_val, \
+                                  arg2_name, arg2_val)
+#define TRACE_EVENT_WITH_FLOW2(category_group, name, bind_id, flow_flags,    \
+                               arg1_name, arg1_val, arg2_name, arg2_val)     \
+  INTERNAL_TRACE_MEMORY(category_group, name)                                \
+  INTERNAL_TRACE_EVENT_ADD_SCOPED_WITH_FLOW(category_group, name, bind_id,   \
+                                            flow_flags, arg1_name, arg1_val, \
+                                            arg2_name, arg2_val)
+
+// Records events like TRACE_EVENT2 but uses |memory_tag| for memory tracing.
+// Use this where |name| is too generic to accurately aggregate allocations.
+#define TRACE_EVENT_WITH_MEMORY_TAG2(category, name, memory_tag, arg1_name, \
+                                     arg1_val, arg2_name, arg2_val)         \
+  INTERNAL_TRACE_MEMORY(category, memory_tag)                               \
+  INTERNAL_TRACE_EVENT_ADD_SCOPED(category, name, arg1_name, arg1_val,      \
+                                  arg2_name, arg2_val)
+
+// UNSHIPPED_TRACE_EVENT* are like TRACE_EVENT* except that they are not
+// included in official builds.
+
+#if OFFICIAL_BUILD
+#undef TRACING_IS_OFFICIAL_BUILD
+#define TRACING_IS_OFFICIAL_BUILD 1
+#elif !defined(TRACING_IS_OFFICIAL_BUILD)
+#define TRACING_IS_OFFICIAL_BUILD 0
+#endif
+
+#if TRACING_IS_OFFICIAL_BUILD
+#define UNSHIPPED_TRACE_EVENT0(category_group, name) (void)0
+#define UNSHIPPED_TRACE_EVENT1(category_group, name, arg1_name, arg1_val) \
+  (void)0
+#define UNSHIPPED_TRACE_EVENT2(category_group, name, arg1_name, arg1_val, \
+                               arg2_name, arg2_val)                       \
+  (void)0
+#define UNSHIPPED_TRACE_EVENT_INSTANT0(category_group, name, scope) (void)0
+#define UNSHIPPED_TRACE_EVENT_INSTANT1(category_group, name, scope, arg1_name, \
+                                       arg1_val)                               \
+  (void)0
+#define UNSHIPPED_TRACE_EVENT_INSTANT2(category_group, name, scope, arg1_name, \
+                                       arg1_val, arg2_name, arg2_val)          \
+  (void)0
+#else
+#define UNSHIPPED_TRACE_EVENT0(category_group, name) \
+  TRACE_EVENT0(category_group, name)
+#define UNSHIPPED_TRACE_EVENT1(category_group, name, arg1_name, arg1_val) \
+  TRACE_EVENT1(category_group, name, arg1_name, arg1_val)
+#define UNSHIPPED_TRACE_EVENT2(category_group, name, arg1_name, arg1_val, \
+                               arg2_name, arg2_val)                       \
+  TRACE_EVENT2(category_group, name, arg1_name, arg1_val, arg2_name, arg2_val)
+#define UNSHIPPED_TRACE_EVENT_INSTANT0(category_group, name, scope) \
+  TRACE_EVENT_INSTANT0(category_group, name, scope)
+#define UNSHIPPED_TRACE_EVENT_INSTANT1(category_group, name, scope, arg1_name, \
+                                       arg1_val)                               \
+  TRACE_EVENT_INSTANT1(category_group, name, scope, arg1_name, arg1_val)
+#define UNSHIPPED_TRACE_EVENT_INSTANT2(category_group, name, scope, arg1_name, \
+                                       arg1_val, arg2_name, arg2_val)          \
+  TRACE_EVENT_INSTANT2(category_group, name, scope, arg1_name, arg1_val,       \
+                       arg2_name, arg2_val)
+#endif
+
+// 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_group, name, scope)                   \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_INSTANT, category_group, name, \
+                           TRACE_EVENT_FLAG_NONE | scope)
+#define TRACE_EVENT_INSTANT1(category_group, name, scope, arg1_name, arg1_val) \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_INSTANT, category_group, name,    \
+                           TRACE_EVENT_FLAG_NONE | scope, arg1_name, arg1_val)
+#define TRACE_EVENT_INSTANT2(category_group, name, scope, arg1_name, arg1_val, \
+                             arg2_name, arg2_val)                              \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_INSTANT, category_group, name,    \
+                           TRACE_EVENT_FLAG_NONE | scope, arg1_name, arg1_val, \
+                           arg2_name, arg2_val)
+#define TRACE_EVENT_COPY_INSTANT0(category_group, name, scope)              \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_INSTANT, category_group, name, \
+                           TRACE_EVENT_FLAG_COPY | scope)
+#define TRACE_EVENT_COPY_INSTANT1(category_group, name, scope, arg1_name,   \
+                                  arg1_val)                                 \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_INSTANT, category_group, name, \
+                           TRACE_EVENT_FLAG_COPY | scope, arg1_name, arg1_val)
+#define TRACE_EVENT_COPY_INSTANT2(category_group, name, scope, arg1_name,      \
+                                  arg1_val, arg2_name, arg2_val)               \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_INSTANT, category_group, name,    \
+                           TRACE_EVENT_FLAG_COPY | scope, arg1_name, arg1_val, \
+                           arg2_name, arg2_val)
+
+// 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)
+
+// 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_group, name)                          \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_BEGIN, category_group, name, \
+                           TRACE_EVENT_FLAG_NONE)
+#define TRACE_EVENT_BEGIN1(category_group, name, arg1_name, arg1_val)     \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_BEGIN, category_group, name, \
+                           TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val)
+#define TRACE_EVENT_BEGIN2(category_group, name, arg1_name, arg1_val,     \
+                           arg2_name, arg2_val)                           \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_BEGIN, category_group, name, \
+                           TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val,    \
+                           arg2_name, arg2_val)
+#define TRACE_EVENT_COPY_BEGIN0(category_group, name)                     \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_BEGIN, category_group, name, \
+                           TRACE_EVENT_FLAG_COPY)
+#define TRACE_EVENT_COPY_BEGIN1(category_group, name, arg1_name, arg1_val) \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_BEGIN, category_group, name,  \
+                           TRACE_EVENT_FLAG_COPY, arg1_name, arg1_val)
+#define TRACE_EVENT_COPY_BEGIN2(category_group, name, arg1_name, arg1_val, \
+                                arg2_name, arg2_val)                       \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_BEGIN, category_group, name,  \
+                           TRACE_EVENT_FLAG_COPY, arg1_name, arg1_val,     \
+                           arg2_name, arg2_val)
+
+// Similar to TRACE_EVENT_BEGINx but with a custom |at| timestamp provided.
+// - |id| is used to match the _BEGIN event with the _END event.
+//   Events are considered to match if their category_group, 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.
+#define TRACE_EVENT_BEGIN_WITH_ID_TID_AND_TIMESTAMP0(category_group, name, id, \
+                                                     thread_id, timestamp)     \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID_TID_AND_TIMESTAMP(                          \
+      TRACE_EVENT_PHASE_ASYNC_BEGIN, category_group, name, id, thread_id,      \
+      timestamp, TRACE_EVENT_FLAG_NONE)
+#define TRACE_EVENT_COPY_BEGIN_WITH_ID_TID_AND_TIMESTAMP0(                \
+    category_group, name, id, thread_id, timestamp)                       \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID_TID_AND_TIMESTAMP(                     \
+      TRACE_EVENT_PHASE_ASYNC_BEGIN, category_group, name, id, thread_id, \
+      timestamp, TRACE_EVENT_FLAG_COPY)
+#define TRACE_EVENT_COPY_BEGIN_WITH_ID_TID_AND_TIMESTAMP1(                \
+    category_group, name, id, thread_id, timestamp, arg1_name, arg1_val)  \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID_TID_AND_TIMESTAMP(                     \
+      TRACE_EVENT_PHASE_ASYNC_BEGIN, category_group, name, id, thread_id, \
+      timestamp, TRACE_EVENT_FLAG_COPY, arg1_name, arg1_val)
+#define TRACE_EVENT_COPY_BEGIN_WITH_ID_TID_AND_TIMESTAMP2(                \
+    category_group, name, id, thread_id, timestamp, arg1_name, arg1_val,  \
+    arg2_name, arg2_val)                                                  \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID_TID_AND_TIMESTAMP(                     \
+      TRACE_EVENT_PHASE_ASYNC_BEGIN, category_group, name, id, thread_id, \
+      timestamp, 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_group, name)                          \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_END, category_group, name, \
+                           TRACE_EVENT_FLAG_NONE)
+#define TRACE_EVENT_END1(category_group, name, arg1_name, arg1_val)     \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_END, category_group, name, \
+                           TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val)
+#define TRACE_EVENT_END2(category_group, name, arg1_name, arg1_val, arg2_name, \
+                         arg2_val)                                             \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_END, category_group, name,        \
+                           TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val,         \
+                           arg2_name, arg2_val)
+#define TRACE_EVENT_COPY_END0(category_group, name)                     \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_END, category_group, name, \
+                           TRACE_EVENT_FLAG_COPY)
+#define TRACE_EVENT_COPY_END1(category_group, name, arg1_name, arg1_val) \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_END, category_group, name,  \
+                           TRACE_EVENT_FLAG_COPY, arg1_name, arg1_val)
+#define TRACE_EVENT_COPY_END2(category_group, name, arg1_name, arg1_val, \
+                              arg2_name, arg2_val)                       \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_END, category_group, name,  \
+                           TRACE_EVENT_FLAG_COPY, arg1_name, arg1_val,   \
+                           arg2_name, arg2_val)
+
+#define TRACE_EVENT_MARK(category_group, name)                           \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_MARK, category_group, name, \
+                           TRACE_EVENT_FLAG_NONE)
+
+#define TRACE_EVENT_MARK_WITH_TIMESTAMP(category_group, name, timestamp)   \
+  INTERNAL_TRACE_EVENT_ADD_WITH_TIMESTAMP(TRACE_EVENT_PHASE_MARK,          \
+                                          category_group, name, timestamp, \
+                                          TRACE_EVENT_FLAG_NONE)
+
+#define TRACE_EVENT_COPY_MARK(category_group, name)                      \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_MARK, category_group, name, \
+                           TRACE_EVENT_FLAG_COPY)
+
+#define TRACE_EVENT_COPY_MARK_WITH_TIMESTAMP(category_group, name, timestamp) \
+  INTERNAL_TRACE_EVENT_ADD_WITH_TIMESTAMP(TRACE_EVENT_PHASE_MARK,             \
+                                          category_group, name, timestamp,    \
+                                          TRACE_EVENT_FLAG_COPY)
+
+// Similar to TRACE_EVENT_ENDx but with a custom |at| timestamp provided.
+// - |id| is used to match the _BEGIN event with the _END event.
+//   Events are considered to match if their category_group, 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.
+#define TRACE_EVENT_END_WITH_ID_TID_AND_TIMESTAMP0(category_group, name, id, \
+                                                   thread_id, timestamp)     \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID_TID_AND_TIMESTAMP(                        \
+      TRACE_EVENT_PHASE_ASYNC_END, category_group, name, id, thread_id,      \
+      timestamp, TRACE_EVENT_FLAG_NONE)
+#define TRACE_EVENT_COPY_END_WITH_ID_TID_AND_TIMESTAMP0(                \
+    category_group, name, id, thread_id, timestamp)                     \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID_TID_AND_TIMESTAMP(                   \
+      TRACE_EVENT_PHASE_ASYNC_END, category_group, name, id, thread_id, \
+      timestamp, TRACE_EVENT_FLAG_COPY)
+#define TRACE_EVENT_COPY_END_WITH_ID_TID_AND_TIMESTAMP1(                 \
+    category_group, name, id, thread_id, timestamp, arg1_name, arg1_val) \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID_TID_AND_TIMESTAMP(                    \
+      TRACE_EVENT_PHASE_ASYNC_END, category_group, name, id, thread_id,  \
+      timestamp, TRACE_EVENT_FLAG_COPY, arg1_name, arg1_val)
+#define TRACE_EVENT_COPY_END_WITH_ID_TID_AND_TIMESTAMP2(                 \
+    category_group, name, id, thread_id, timestamp, arg1_name, arg1_val, \
+    arg2_name, arg2_val)                                                 \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID_TID_AND_TIMESTAMP(                    \
+      TRACE_EVENT_PHASE_ASYNC_END, category_group, name, id, thread_id,  \
+      timestamp, 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_group, name, value)                         \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_COUNTER, category_group, name, \
+                           TRACE_EVENT_FLAG_NONE, "value",                  \
+                           static_cast<int>(value))
+#define TRACE_COPY_COUNTER1(category_group, name, value)                    \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_COUNTER, category_group, 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_group, name, value1_name, value1_val,       \
+                       value2_name, value2_val)                             \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_COUNTER, category_group, name, \
+                           TRACE_EVENT_FLAG_NONE, value1_name,              \
+                           static_cast<int>(value1_val), value2_name,       \
+                           static_cast<int>(value2_val))
+#define TRACE_COPY_COUNTER2(category_group, name, value1_name, value1_val,  \
+                            value2_name, value2_val)                        \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_COUNTER, category_group, 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_group, name, id, value)                    \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_COUNTER, category_group, \
+                                   name, id, TRACE_EVENT_FLAG_NONE, "value",  \
+                                   static_cast<int>(value))
+#define TRACE_COPY_COUNTER_ID1(category_group, name, id, value)               \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_COUNTER, category_group, \
+                                   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_group, name, id, value1_name, value1_val,  \
+                          value2_name, value2_val)                            \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_COUNTER, category_group, \
+                                   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_group, name, id, value1_name,         \
+                               value1_val, value2_name, value2_val)           \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_COUNTER, category_group, \
+                                   name, id, TRACE_EVENT_FLAG_COPY,           \
+                                   value1_name, static_cast<int>(value1_val), \
+                                   value2_name, static_cast<int>(value2_val))
+
+// TRACE_EVENT_SAMPLE_* events are injected by the sampling profiler.
+#define TRACE_EVENT_SAMPLE_WITH_TID_AND_TIMESTAMP0(category_group, name,       \
+                                                   thread_id, timestamp)       \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID_TID_AND_TIMESTAMP(                          \
+      TRACE_EVENT_PHASE_SAMPLE, category_group, name, 0, thread_id, timestamp, \
+      TRACE_EVENT_FLAG_NONE)
+
+#define TRACE_EVENT_SAMPLE_WITH_TID_AND_TIMESTAMP1(                            \
+    category_group, name, thread_id, timestamp, arg1_name, arg1_val)           \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID_TID_AND_TIMESTAMP(                          \
+      TRACE_EVENT_PHASE_SAMPLE, category_group, name, 0, thread_id, timestamp, \
+      TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val)
+
+#define TRACE_EVENT_SAMPLE_WITH_TID_AND_TIMESTAMP2(category_group, name,       \
+                                                   thread_id, timestamp,       \
+                                                   arg1_name, arg1_val,        \
+                                                   arg2_name, arg2_val)        \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID_TID_AND_TIMESTAMP(                          \
+      TRACE_EVENT_PHASE_SAMPLE, category_group, name, 0, thread_id, timestamp, \
+      TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val, arg2_name, arg2_val)
+
+// ASYNC_STEP_* APIs should be only used by legacy code. New code should
+// consider using NESTABLE_ASYNC_* APIs to describe substeps within an async
+// event.
+// 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_group, 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
+// args.
+#define TRACE_EVENT_ASYNC_BEGIN0(category_group, name, id)        \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_BEGIN, \
+                                   category_group, name, id,      \
+                                   TRACE_EVENT_FLAG_NONE)
+#define TRACE_EVENT_ASYNC_BEGIN1(category_group, name, id, arg1_name, \
+                                 arg1_val)                            \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_BEGIN,     \
+                                   category_group, name, id,          \
+                                   TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val)
+#define TRACE_EVENT_ASYNC_BEGIN2(category_group, name, id, arg1_name, \
+                                 arg1_val, arg2_name, arg2_val)       \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(                                   \
+      TRACE_EVENT_PHASE_ASYNC_BEGIN, category_group, name, id,        \
+      TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val, arg2_name, arg2_val)
+#define TRACE_EVENT_COPY_ASYNC_BEGIN0(category_group, name, id)   \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_BEGIN, \
+                                   category_group, name, id,      \
+                                   TRACE_EVENT_FLAG_COPY)
+#define TRACE_EVENT_COPY_ASYNC_BEGIN1(category_group, name, id, arg1_name, \
+                                      arg1_val)                            \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_BEGIN,          \
+                                   category_group, name, id,               \
+                                   TRACE_EVENT_FLAG_COPY, arg1_name, arg1_val)
+#define TRACE_EVENT_COPY_ASYNC_BEGIN2(category_group, name, id, arg1_name, \
+                                      arg1_val, arg2_name, arg2_val)       \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(                                        \
+      TRACE_EVENT_PHASE_ASYNC_BEGIN, category_group, name, id,             \
+      TRACE_EVENT_FLAG_COPY, arg1_name, arg1_val, arg2_name, arg2_val)
+
+// Similar to TRACE_EVENT_ASYNC_BEGINx but with a custom |at| timestamp
+// provided.
+#define TRACE_EVENT_ASYNC_BEGIN_WITH_TIMESTAMP0(category_group, name, id, \
+                                                timestamp)                \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID_TID_AND_TIMESTAMP(                     \
+      TRACE_EVENT_PHASE_ASYNC_BEGIN, category_group, name, id,            \
+      TRACE_EVENT_API_CURRENT_THREAD_ID, timestamp, TRACE_EVENT_FLAG_NONE)
+#define TRACE_EVENT_COPY_ASYNC_BEGIN_WITH_TIMESTAMP0(category_group, name, id, \
+                                                     timestamp)                \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID_TID_AND_TIMESTAMP(                          \
+      TRACE_EVENT_PHASE_ASYNC_BEGIN, category_group, name, id,                 \
+      TRACE_EVENT_API_CURRENT_THREAD_ID, timestamp, TRACE_EVENT_FLAG_COPY)
+
+// 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_group, name, id, step)  \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_STEP_INTO, \
+                                   category_group, name, id,          \
+                                   TRACE_EVENT_FLAG_NONE, "step", step)
+#define TRACE_EVENT_ASYNC_STEP_INTO1(category_group, name, id, step, \
+                                     arg1_name, arg1_val)            \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(                                  \
+      TRACE_EVENT_PHASE_ASYNC_STEP_INTO, category_group, name, id,   \
+      TRACE_EVENT_FLAG_NONE, "step", step, arg1_name, arg1_val)
+
+// Similar to TRACE_EVENT_ASYNC_STEP_INTOx but with a custom |at| timestamp
+// provided.
+#define TRACE_EVENT_ASYNC_STEP_INTO_WITH_TIMESTAMP0(category_group, name, id, \
+                                                    step, timestamp)          \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID_TID_AND_TIMESTAMP(                         \
+      TRACE_EVENT_PHASE_ASYNC_STEP_INTO, category_group, name, id,            \
+      TRACE_EVENT_API_CURRENT_THREAD_ID, timestamp, TRACE_EVENT_FLAG_NONE,    \
+      "step", step)
+
+// 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_group, name, id)        \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_END, \
+                                   category_group, name, id,    \
+                                   TRACE_EVENT_FLAG_NONE)
+#define TRACE_EVENT_ASYNC_END1(category_group, name, id, arg1_name, arg1_val) \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_END,               \
+                                   category_group, name, id,                  \
+                                   TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val)
+#define TRACE_EVENT_ASYNC_END2(category_group, name, id, arg1_name, arg1_val, \
+                               arg2_name, arg2_val)                           \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(                                           \
+      TRACE_EVENT_PHASE_ASYNC_END, category_group, name, id,                  \
+      TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val, arg2_name, arg2_val)
+#define TRACE_EVENT_COPY_ASYNC_END0(category_group, name, id)   \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_END, \
+                                   category_group, name, id,    \
+                                   TRACE_EVENT_FLAG_COPY)
+#define TRACE_EVENT_COPY_ASYNC_END1(category_group, name, id, arg1_name, \
+                                    arg1_val)                            \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_ASYNC_END,          \
+                                   category_group, name, id,             \
+                                   TRACE_EVENT_FLAG_COPY, arg1_name, arg1_val)
+#define TRACE_EVENT_COPY_ASYNC_END2(category_group, name, id, arg1_name, \
+                                    arg1_val, arg2_name, arg2_val)       \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(                                      \
+      TRACE_EVENT_PHASE_ASYNC_END, category_group, name, id,             \
+      TRACE_EVENT_FLAG_COPY, arg1_name, arg1_val, arg2_name, arg2_val)
+
+// Similar to TRACE_EVENT_ASYNC_ENDx but with a custom |at| timestamp provided.
+#define TRACE_EVENT_ASYNC_END_WITH_TIMESTAMP0(category_group, name, id, \
+                                              timestamp)                \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID_TID_AND_TIMESTAMP(                   \
+      TRACE_EVENT_PHASE_ASYNC_END, category_group, name, id,            \
+      TRACE_EVENT_API_CURRENT_THREAD_ID, timestamp, TRACE_EVENT_FLAG_NONE)
+
+// NESTABLE_ASYNC_* APIs are used to describe an async operation, which can
+// be nested within a NESTABLE_ASYNC event and/or have inner NESTABLE_ASYNC
+// events.
+// - category and name strings must have application lifetime (statics or
+//   literals). They may not include " chars.
+// - A pair of NESTABLE_ASYNC_BEGIN event and NESTABLE_ASYNC_END event is
+//   considered as a match if their category_group, name and id 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.
+// - |id| is used to match a child NESTABLE_ASYNC event with its parent
+//   NESTABLE_ASYNC event. Therefore, events in the same nested event tree must
+//   be logged using the same id and category_group.
+//
+// Unmatched NESTABLE_ASYNC_END event will be parsed as an event that starts
+// at the first NESTABLE_ASYNC event of that id, and unmatched
+// NESTABLE_ASYNC_BEGIN event will be parsed as an event that ends at the last
+// NESTABLE_ASYNC event of that id. Corresponding warning messages for
+// unmatched events will be shown in the analysis view.
+
+// Records a single NESTABLE_ASYNC_BEGIN event called "name" immediately, with
+// 0, 1 or 2 associated arguments. If the category is not enabled, then this
+// does nothing.
+#define TRACE_EVENT_NESTABLE_ASYNC_BEGIN0(category_group, name, id)        \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_NESTABLE_ASYNC_BEGIN, \
+                                   category_group, name, id,               \
+                                   TRACE_EVENT_FLAG_NONE)
+#define TRACE_EVENT_NESTABLE_ASYNC_BEGIN1(category_group, name, id, arg1_name, \
+                                          arg1_val)                            \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_NESTABLE_ASYNC_BEGIN,     \
+                                   category_group, name, id,                   \
+                                   TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val)
+#define TRACE_EVENT_NESTABLE_ASYNC_BEGIN2(category_group, name, id, arg1_name, \
+                                          arg1_val, arg2_name, arg2_val)       \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(                                            \
+      TRACE_EVENT_PHASE_NESTABLE_ASYNC_BEGIN, category_group, name, id,        \
+      TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val, arg2_name, arg2_val)
+// Records a single NESTABLE_ASYNC_END event called "name" immediately, with 0
+// or 2 associated arguments. If the category is not enabled, then this does
+// nothing.
+#define TRACE_EVENT_NESTABLE_ASYNC_END0(category_group, name, id)        \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_NESTABLE_ASYNC_END, \
+                                   category_group, name, id,             \
+                                   TRACE_EVENT_FLAG_NONE)
+// Records a single NESTABLE_ASYNC_END event called "name" immediately, with 1
+// associated argument. If the category is not enabled, then this does nothing.
+#define TRACE_EVENT_NESTABLE_ASYNC_END1(category_group, name, id, arg1_name, \
+                                        arg1_val)                            \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_NESTABLE_ASYNC_END,     \
+                                   category_group, name, id,                 \
+                                   TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val)
+#define TRACE_EVENT_NESTABLE_ASYNC_END2(category_group, name, id, arg1_name, \
+                                        arg1_val, arg2_name, arg2_val)       \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(                                          \
+      TRACE_EVENT_PHASE_NESTABLE_ASYNC_END, category_group, name, id,        \
+      TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val, arg2_name, arg2_val)
+
+// Records a single NESTABLE_ASYNC_INSTANT event called "name" immediately,
+// with one associated argument. If the category is not enabled, then this
+// does nothing.
+#define TRACE_EVENT_NESTABLE_ASYNC_INSTANT1(category_group, name, id,        \
+                                            arg1_name, arg1_val)             \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_NESTABLE_ASYNC_INSTANT, \
+                                   category_group, name, id,                 \
+                                   TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val)
+// Records a single NESTABLE_ASYNC_INSTANT event called "name" immediately,
+// with 2 associated arguments. If the category is not enabled, then this
+// does nothing.
+#define TRACE_EVENT_NESTABLE_ASYNC_INSTANT2(                              \
+    category_group, name, id, arg1_name, arg1_val, arg2_name, arg2_val)   \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(                                       \
+      TRACE_EVENT_PHASE_NESTABLE_ASYNC_INSTANT, category_group, name, id, \
+      TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val, arg2_name, arg2_val)
+
+#define TRACE_EVENT_COPY_NESTABLE_ASYNC_BEGIN_WITH_TTS2(                       \
+    category_group, name, id, arg1_name, arg1_val, arg2_name, arg2_val)        \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(                                            \
+      TRACE_EVENT_PHASE_NESTABLE_ASYNC_BEGIN, category_group, name, id,        \
+      TRACE_EVENT_FLAG_ASYNC_TTS | TRACE_EVENT_FLAG_COPY, arg1_name, arg1_val, \
+      arg2_name, arg2_val)
+#define TRACE_EVENT_COPY_NESTABLE_ASYNC_END_WITH_TTS2(                         \
+    category_group, name, id, arg1_name, arg1_val, arg2_name, arg2_val)        \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(                                            \
+      TRACE_EVENT_PHASE_NESTABLE_ASYNC_END, category_group, name, id,          \
+      TRACE_EVENT_FLAG_ASYNC_TTS | TRACE_EVENT_FLAG_COPY, arg1_name, arg1_val, \
+      arg2_name, arg2_val)
+
+// Similar to TRACE_EVENT_NESTABLE_ASYNC_{BEGIN,END}x but with a custom
+// |timestamp| provided.
+#define TRACE_EVENT_NESTABLE_ASYNC_BEGIN_WITH_TIMESTAMP0(category_group, name, \
+                                                         id, timestamp)        \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID_TID_AND_TIMESTAMP(                          \
+      TRACE_EVENT_PHASE_NESTABLE_ASYNC_BEGIN, category_group, name, id,        \
+      TRACE_EVENT_API_CURRENT_THREAD_ID, timestamp, TRACE_EVENT_FLAG_NONE)
+
+#define TRACE_EVENT_NESTABLE_ASYNC_END_WITH_TIMESTAMP0(category_group, name, \
+                                                       id, timestamp)        \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID_TID_AND_TIMESTAMP(                        \
+      TRACE_EVENT_PHASE_NESTABLE_ASYNC_END, category_group, name, id,        \
+      TRACE_EVENT_API_CURRENT_THREAD_ID, timestamp, TRACE_EVENT_FLAG_NONE)
+
+#define TRACE_EVENT_COPY_NESTABLE_ASYNC_BEGIN_WITH_TIMESTAMP0(          \
+    category_group, name, id, timestamp)                                \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID_AND_TIMESTAMP(                       \
+      TRACE_EVENT_PHASE_NESTABLE_ASYNC_BEGIN, category_group, name, id, \
+      timestamp, TRACE_EVENT_FLAG_COPY)
+#define TRACE_EVENT_COPY_NESTABLE_ASYNC_END_WITH_TIMESTAMP0(          \
+    category_group, name, id, timestamp)                              \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID_AND_TIMESTAMP(                     \
+      TRACE_EVENT_PHASE_NESTABLE_ASYNC_END, category_group, name, id, \
+      timestamp, TRACE_EVENT_FLAG_COPY)
+
+// Records a single NESTABLE_ASYNC_INSTANT event called "name" immediately,
+// with 2 associated arguments. If the category is not enabled, then this
+// does nothing.
+#define TRACE_EVENT_NESTABLE_ASYNC_INSTANT2(                              \
+    category_group, name, id, arg1_name, arg1_val, arg2_name, arg2_val)   \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(                                       \
+      TRACE_EVENT_PHASE_NESTABLE_ASYNC_INSTANT, category_group, name, id, \
+      TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val, arg2_name, arg2_val)
+
+// Records a single FLOW_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 FLOW_BEGIN event with the FLOW_END event. FLOW
+//   events are considered to match if their category_group, 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.
+// FLOW events are different from ASYNC events in how they are drawn by the
+// tracing UI. A FLOW defines asynchronous data flow, such as posting a task
+// (FLOW_BEGIN) and later executing that task (FLOW_END). Expect FLOWs to be
+// drawn as lines or arrows from FLOW_BEGIN scopes to FLOW_END scopes. Similar
+// to ASYNC, a FLOW can consist of multiple phases. The first phase is defined
+// by the FLOW_BEGIN calls. Additional phases can be defined using the FLOW_STEP
+// macros. When the operation completes, call FLOW_END. An async operation can
+// span threads and processes, but all events in that operation must use the
+// same |name| and |id|. Each event can have its own args.
+#define TRACE_EVENT_FLOW_BEGIN0(category_group, name, id)        \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_BEGIN, \
+                                   category_group, name, id,     \
+                                   TRACE_EVENT_FLAG_NONE)
+#define TRACE_EVENT_FLOW_BEGIN1(category_group, name, id, arg1_name, arg1_val) \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_BEGIN,               \
+                                   category_group, name, id,                   \
+                                   TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val)
+#define TRACE_EVENT_FLOW_BEGIN2(category_group, name, id, arg1_name, arg1_val, \
+                                arg2_name, arg2_val)                           \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(                                            \
+      TRACE_EVENT_PHASE_FLOW_BEGIN, category_group, name, id,                  \
+      TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val, arg2_name, arg2_val)
+#define TRACE_EVENT_COPY_FLOW_BEGIN0(category_group, name, id)   \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_BEGIN, \
+                                   category_group, name, id,     \
+                                   TRACE_EVENT_FLAG_COPY)
+#define TRACE_EVENT_COPY_FLOW_BEGIN1(category_group, name, id, arg1_name, \
+                                     arg1_val)                            \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_BEGIN,          \
+                                   category_group, name, id,              \
+                                   TRACE_EVENT_FLAG_COPY, arg1_name, arg1_val)
+#define TRACE_EVENT_COPY_FLOW_BEGIN2(category_group, name, id, arg1_name, \
+                                     arg1_val, arg2_name, arg2_val)       \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(                                       \
+      TRACE_EVENT_PHASE_FLOW_BEGIN, category_group, name, id,             \
+      TRACE_EVENT_FLAG_COPY, arg1_name, arg1_val, arg2_name, arg2_val)
+
+// Records a single FLOW_STEP event for |step| immediately. If the category
+// is not enabled, then this does nothing. The |name| and |id| must match the
+// FLOW_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.
+#define TRACE_EVENT_FLOW_STEP0(category_group, name, id, step)  \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_STEP, \
+                                   category_group, name, id,    \
+                                   TRACE_EVENT_FLAG_NONE, "step", step)
+#define TRACE_EVENT_FLOW_STEP1(category_group, name, id, step, arg1_name, \
+                               arg1_val)                                  \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(                                       \
+      TRACE_EVENT_PHASE_FLOW_STEP, category_group, name, id,              \
+      TRACE_EVENT_FLAG_NONE, "step", step, arg1_name, arg1_val)
+#define TRACE_EVENT_COPY_FLOW_STEP0(category_group, name, id, step) \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_STEP,     \
+                                   category_group, name, id,        \
+                                   TRACE_EVENT_FLAG_COPY, "step", step)
+#define TRACE_EVENT_COPY_FLOW_STEP1(category_group, name, id, step, arg1_name, \
+                                    arg1_val)                                  \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(                                            \
+      TRACE_EVENT_PHASE_FLOW_STEP, category_group, name, id,                   \
+      TRACE_EVENT_FLAG_COPY, "step", step, arg1_name, arg1_val)
+
+// Records a single FLOW_END event for "name" immediately. If the category
+// is not enabled, then this does nothing.
+#define TRACE_EVENT_FLOW_END0(category_group, name, id)                        \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_END, category_group, \
+                                   name, id, TRACE_EVENT_FLAG_NONE)
+#define TRACE_EVENT_FLOW_END_BIND_TO_ENCLOSING0(category_group, name, id)      \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_END, category_group, \
+                                   name, id,                                   \
+                                   TRACE_EVENT_FLAG_BIND_TO_ENCLOSING)
+#define TRACE_EVENT_FLOW_END1(category_group, name, id, arg1_name, arg1_val)   \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_END, category_group, \
+                                   name, id, TRACE_EVENT_FLAG_NONE, arg1_name, \
+                                   arg1_val)
+#define TRACE_EVENT_FLOW_END2(category_group, name, id, arg1_name, arg1_val,   \
+                              arg2_name, arg2_val)                             \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_END, category_group, \
+                                   name, id, TRACE_EVENT_FLAG_NONE, arg1_name, \
+                                   arg1_val, arg2_name, arg2_val)
+#define TRACE_EVENT_COPY_FLOW_END0(category_group, name, id)                   \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_END, category_group, \
+                                   name, id, TRACE_EVENT_FLAG_COPY)
+#define TRACE_EVENT_COPY_FLOW_END1(category_group, name, id, arg1_name,        \
+                                   arg1_val)                                   \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_END, category_group, \
+                                   name, id, TRACE_EVENT_FLAG_COPY, arg1_name, \
+                                   arg1_val)
+#define TRACE_EVENT_COPY_FLOW_END2(category_group, name, id, arg1_name,        \
+                                   arg1_val, arg2_name, arg2_val)              \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(TRACE_EVENT_PHASE_FLOW_END, category_group, \
+                                   name, id, TRACE_EVENT_FLAG_COPY, arg1_name, \
+                                   arg1_val, arg2_name, arg2_val)
+
+// Macros to track the life time and value of arbitrary client objects.
+// See also TraceTrackableObject.
+#define TRACE_EVENT_OBJECT_CREATED_WITH_ID(category_group, name, id) \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(                                  \
+      TRACE_EVENT_PHASE_CREATE_OBJECT, category_group, name,         \
+      TRACE_ID_DONT_MANGLE(id), TRACE_EVENT_FLAG_NONE)
+
+#define TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID(category_group, name, id, \
+                                            snapshot)                 \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(                                   \
+      TRACE_EVENT_PHASE_SNAPSHOT_OBJECT, category_group, name,        \
+      TRACE_ID_DONT_MANGLE(id), TRACE_EVENT_FLAG_NONE, "snapshot", snapshot)
+
+#define TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID_AND_TIMESTAMP(                    \
+    category_group, name, id, timestamp, snapshot)                            \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID_TID_AND_TIMESTAMP(                         \
+      TRACE_EVENT_PHASE_SNAPSHOT_OBJECT, category_group, name,                \
+      TRACE_ID_DONT_MANGLE(id), TRACE_EVENT_API_CURRENT_THREAD_ID, timestamp, \
+      TRACE_EVENT_FLAG_NONE, "snapshot", snapshot)
+
+#define TRACE_EVENT_OBJECT_DELETED_WITH_ID(category_group, name, id) \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID(                                  \
+      TRACE_EVENT_PHASE_DELETE_OBJECT, category_group, 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(category_group, ret)             \
+  do {                                                                      \
+    INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category_group);                 \
+    if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE()) { \
+      *ret = true;                                                          \
+    } else {                                                                \
+      *ret = false;                                                         \
+    }                                                                       \
+  } while (0)
+
+// Macro to explicitly warm up a given category group. This could be useful in
+// cases where we want to initialize a category group before any trace events
+// for that category group is reported. For example, to have a category group
+// always show up in the "record categories" list for manually selecting
+// settings in about://tracing.
+#define TRACE_EVENT_WARMUP_CATEGORY(category_group) \
+  INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category_group)
+
+// Macro to efficiently determine, through polling, if a new trace has begun.
+#define TRACE_EVENT_IS_NEW_TRACE(ret)                                      \
+  do {                                                                     \
+    static int INTERNAL_TRACE_EVENT_UID(lastRecordingNumber) = 0;          \
+    int num_traces_recorded = TRACE_EVENT_API_GET_NUM_TRACES_RECORDED();   \
+    if (num_traces_recorded != -1 &&                                       \
+        num_traces_recorded !=                                             \
+            INTERNAL_TRACE_EVENT_UID(lastRecordingNumber)) {               \
+      INTERNAL_TRACE_EVENT_UID(lastRecordingNumber) = num_traces_recorded; \
+      *ret = true;                                                         \
+    } else {                                                               \
+      *ret = false;                                                        \
+    }                                                                      \
+  } 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')
+#define TRACE_EVENT_PHASE_INSTANT ('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_NESTABLE_ASYNC_BEGIN ('b')
+#define TRACE_EVENT_PHASE_NESTABLE_ASYNC_END ('e')
+#define TRACE_EVENT_PHASE_NESTABLE_ASYNC_INSTANT ('n')
+#define TRACE_EVENT_PHASE_FLOW_BEGIN ('s')
+#define TRACE_EVENT_PHASE_FLOW_STEP ('t')
+#define TRACE_EVENT_PHASE_FLOW_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_SNAPSHOT_OBJECT ('O')
+#define TRACE_EVENT_PHASE_DELETE_OBJECT ('D')
+#define TRACE_EVENT_PHASE_MEMORY_DUMP ('v')
+#define TRACE_EVENT_PHASE_MARK ('R')
+
+// Flags for changing the behavior of TRACE_EVENT_API_ADD_TRACE_EVENT.
+#define TRACE_EVENT_FLAG_NONE (static_cast<unsigned int>(0))
+#define TRACE_EVENT_FLAG_COPY (static_cast<unsigned int>(1 << 0))
+#define TRACE_EVENT_FLAG_HAS_ID (static_cast<unsigned int>(1 << 1))
+#define TRACE_EVENT_FLAG_MANGLE_ID (static_cast<unsigned int>(1 << 2))
+#define TRACE_EVENT_FLAG_SCOPE_OFFSET (static_cast<unsigned int>(1 << 3))
+#define TRACE_EVENT_FLAG_SCOPE_EXTRA (static_cast<unsigned int>(1 << 4))
+#define TRACE_EVENT_FLAG_EXPLICIT_TIMESTAMP (static_cast<unsigned int>(1 << 5))
+#define TRACE_EVENT_FLAG_ASYNC_TTS (static_cast<unsigned int>(1 << 6))
+#define TRACE_EVENT_FLAG_BIND_TO_ENCLOSING (static_cast<unsigned int>(1 << 7))
+#define TRACE_EVENT_FLAG_FLOW_IN (static_cast<unsigned int>(1 << 8))
+#define TRACE_EVENT_FLAG_FLOW_OUT (static_cast<unsigned int>(1 << 9))
+#define TRACE_EVENT_FLAG_HAS_CONTEXT_ID (static_cast<unsigned int>(1 << 10))
+
+#define TRACE_EVENT_FLAG_SCOPE_MASK                          \
+  (static_cast<unsigned int>(TRACE_EVENT_FLAG_SCOPE_OFFSET | \
+                             TRACE_EVENT_FLAG_SCOPE_EXTRA))
+
+// 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))
+#define TRACE_VALUE_TYPE_CONVERTABLE (static_cast<unsigned char>(8))
+
+// Enum reflecting the scope of an INSTANT event. Must fit within
+// TRACE_EVENT_FLAG_SCOPE_MASK.
+#define TRACE_EVENT_SCOPE_GLOBAL (static_cast<unsigned char>(0 << 3))
+#define TRACE_EVENT_SCOPE_PROCESS (static_cast<unsigned char>(1 << 3))
+#define TRACE_EVENT_SCOPE_THREAD (static_cast<unsigned char>(2 << 3))
+
+#define TRACE_EVENT_SCOPE_NAME_GLOBAL ('g')
+#define TRACE_EVENT_SCOPE_NAME_PROCESS ('p')
+#define TRACE_EVENT_SCOPE_NAME_THREAD ('t')