Tracing: Add metadata indicating whether we have a high-resolution clock available

base/trace_event/trace_event.h

 // Copyright (c) 2012 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.
 
 #ifndef BASE_TRACE_EVENT_TRACE_EVENT_H_
 #define BASE_TRACE_EVENT_TRACE_EVENT_H_
 
 // This header file defines implementation details of how the trace macros in
 // trace_event_common.h collect and store trace events. Anything not
 // implementation-specific should go in trace_macros_common.h instead of here.
@@ skipping 747 matching lines @@
       convertable_values[1] = {arg_value};
   unsigned char arg_types[1] = {TRACE_VALUE_TYPE_CONVERTABLE};
   base::trace_event::TraceLog::GetInstance()->AddMetadataEvent(
       event_name,
       1,  // num_args
       arg_names, arg_types,
       nullptr,  // arg_values
       convertable_values, TRACE_EVENT_FLAG_NONE);
 }
 
+template <class ARG1_TYPE>
+static void AddMetadataEvent(const char* event_name,
+                             const char* arg_name,
+                             const ARG1_TYPE& arg_val) {
+  const int num_args = 1;
+  const char* arg_names[1] = {arg_name};
+  unsigned char arg_types[1];
+  unsigned long long arg_values[1];
+  SetTraceValue(arg_val, &arg_types[0], &arg_values[0]);
+
+  base::trace_event::TraceLog::GetInstance()->AddMetadataEvent(
+      event_name, num_args, arg_names, arg_types, arg_values, nullptr,
+      TRACE_EVENT_FLAG_NONE);
+}
+
 // Used by TRACE_EVENTx macros. Do not use directly.
 class TRACE_EVENT_API_CLASS_EXPORT ScopedTracer {
  public:
   // Note: members of data_ intentionally left uninitialized. See Initialize.
   ScopedTracer() : p_data_(NULL) {}
 
   ~ScopedTracer() {
     if (p_data_ && *data_.category_group_enabled)
       TRACE_EVENT_API_UPDATE_TRACE_EVENT_DURATION(
           data_.category_group_enabled, data_.name, data_.event_handle);
@@ skipping 103 matching lines @@
   const char* name_;
   IDType id_;
 
   DISALLOW_COPY_AND_ASSIGN(TraceScopedTrackableObject);
 };
 
 }  // namespace trace_event
 }  // namespace base
 
 #endif  // BASE_TRACE_EVENT_TRACE_EVENT_H_