Implement a new flow event API that allows binding flow events and regular events.

ui/gl/angle_platform_impl.cc

 // 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.
 
 #include "ui/gl/angle_platform_impl.h"
 
 #include "base/metrics/histogram.h"
 #include "base/metrics/sparse_histogram.h"
 #include "base/trace_event/trace_event.h"
 
@@ skipping 26 matching lines @@
     double timestamp,
     int num_args,
     const char** arg_names,
     const unsigned char* arg_types,
     const unsigned long long* arg_values,
     unsigned char flags) {
   base::TraceTicks timestamp_tt =
       base::TraceTicks() + base::TimeDelta::FromSecondsD(timestamp);
   base::trace_event::TraceEventHandle handle =
       TRACE_EVENT_API_ADD_TRACE_EVENT_WITH_THREAD_ID_AND_TIMESTAMP(
-          phase, category_group_enabled, name, id, trace_event_internal::kNoId,
-          base::PlatformThread::CurrentId(), timestamp_tt, num_args, arg_names,
-          arg_types, arg_values, nullptr, flags);
+          phase,
+          category_group_enabled,
+          name,
+          id,
+          trace_event_internal::kNoId,
+          base::PlatformThread::CurrentId(),

[beaudoin, 2015/07/27 18:34:14]

EOL comments?

+          timestamp_tt,
+          num_args,
+          arg_names,
+          arg_types,
+          arg_values,
+          NULL,
+          flags);
   angle::Platform::TraceEventHandle result;
   memcpy(&result, &handle, sizeof(result));
   return result;
 }
 
 void ANGLEPlatformImpl::updateTraceEventDuration(
     const unsigned char* category_group_enabled,
     const char* name,
     TraceEventHandle handle) {
   base::trace_event::TraceEventHandle trace_event_handle;
@@ skipping 32 matching lines @@
   // For sparse histograms, we can use the macro, as it does not incorporate a
   // static.
   UMA_HISTOGRAM_SPARSE_SLOWLY(name, sample);
 }
 
 void ANGLEPlatformImpl::histogramBoolean(const char* name, bool sample) {
   histogramEnumeration(name, sample ? 1 : 0, 2);
 }
 
 }  // namespace gfx