tracing: remove sampling state profiler

base/trace_event/trace_event.h

Index: base/trace_event/trace_event.h
diff --git a/base/trace_event/trace_event.h b/base/trace_event/trace_event.h
index 4de64837161fded5fd176d1dc5136006d8521a9e..eca7c07010e2732a291a8430875239f567a4348a 100644
--- a/base/trace_event/trace_event.h
+++ b/base/trace_event/trace_event.h
@@ -49,40 +49,6 @@
 #define TRACE_ID_GLOBAL(id) trace_event_internal::TraceID::GlobalId(id)
 #define TRACE_ID_LOCAL(id) trace_event_internal::TraceID::LocalId(id)
 
-// Sets the current sample state to 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.
-#define TRACE_EVENT_SET_SAMPLING_STATE_FOR_BUCKET( \
-    bucket_number, category, name)                 \
-        trace_event_internal::                     \
-        TraceEventSamplingStateScope<bucket_number>::Set(category "\0" name)
-
-// Returns a current sampling state of the given bucket.
-#define TRACE_EVENT_GET_SAMPLING_STATE_FOR_BUCKET(bucket_number) \
-    trace_event_internal::TraceEventSamplingStateScope<bucket_number>::Current()
-
-// Sets a current sampling state of the given bucket.
-// |category_and_name| 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, category_and_name)                       \
-        trace_event_internal::                              \
-        TraceEventSamplingStateScope<bucket_number>::Set(category_and_name)
-
-// Creates a scope of a sampling state of the given bucket.
-//
-// {  // 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)                                      \
-    trace_event_internal::TraceEventSamplingStateScope<bucket_number>   \
-        traceEventSamplingScope(category "\0" name);
-
 #define TRACE_EVENT_API_CURRENT_THREAD_ID \
   static_cast<int>(base::PlatformThread::CurrentId())
 
@@ -232,13 +198,6 @@
 // Defines visibility for classes in trace_event.h
 #define TRACE_EVENT_API_CLASS_EXPORT BASE_EXPORT
 
-// The thread buckets for the sampling profiler.
-TRACE_EVENT_API_CLASS_EXPORT extern \
-    TRACE_EVENT_API_ATOMIC_WORD g_trace_state[3];
-
-#define TRACE_EVENT_API_THREAD_BUCKET(thread_bucket)                           \
-    g_trace_state[thread_bucket]
-
 ////////////////////////////////////////////////////////////////////////////////
 
 // Implementation detail: trace event macros create temporary variables
@@ -1100,37 +1059,6 @@ class TRACE_EVENT_API_CLASS_EXPORT ScopedTraceBinaryEfficient {
     trace_event_internal::ScopedTraceBinaryEfficient \
         INTERNAL_TRACE_EVENT_UID(scoped_trace)(category_group, name);
 
-// 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 TraceEventSamplingStateScope {
- public:
-  TraceEventSamplingStateScope(const char* category_and_name) {
-    previous_state_ = TraceEventSamplingStateScope<BucketNumber>::Current();
-    TraceEventSamplingStateScope<BucketNumber>::Set(category_and_name);
-  }
-
-  ~TraceEventSamplingStateScope() {
-    TraceEventSamplingStateScope<BucketNumber>::Set(previous_state_);
-  }
-
-  static inline const char* Current() {
-    return reinterpret_cast<const char*>(TRACE_EVENT_API_ATOMIC_LOAD(
-      g_trace_state[BucketNumber]));
-  }
-
-  static inline void Set(const char* category_and_name) {
-    TRACE_EVENT_API_ATOMIC_STORE(
-      g_trace_state[BucketNumber],
-      reinterpret_cast<TRACE_EVENT_API_ATOMIC_WORD>(
-        const_cast<char*>(category_and_name)));
-  }
-
- private:
-  const char* previous_state_;
-};
-
 }  // namespace trace_event_internal
 
 namespace base {