Update from https://crrev.com/304418

base/debug/trace_event_impl.cc

 // 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.
 
 #include "base/debug/trace_event_impl.h"
 
 #include <algorithm>
 
 #include "base/base_switches.h"
 #include "base/bind.h"
@@ skipping 1167 matching lines @@
 
   trace_log_->lock_.AssertAcquired();
   if (trace_log_->CheckGeneration(generation_)) {
     // Return the chunk to the buffer only if the generation matches.
     trace_log_->logged_events_->ReturnChunk(chunk_index_, chunk_.Pass());
   }
   // Otherwise this method may be called from the destructor, or TraceLog will
   // find the generation mismatch and delete this buffer soon.
 }
 
+TraceLogStatus::TraceLogStatus() : event_capacity(0), event_count(0) {
+}
+
+TraceLogStatus::~TraceLogStatus() {
+}
+
 // static
 TraceLog* TraceLog::GetInstance() {
   return Singleton<TraceLog, LeakySingletonTraits<TraceLog> >::get();
 }
 
 TraceLog::TraceLog()
     : mode_(DISABLED),
       num_traces_recorded_(0),
       event_callback_(0),
       dispatching_to_observer_list_(false),
@@ skipping 381 matching lines @@
 }
 
 bool TraceLog::HasEnabledStateObserver(EnabledStateObserver* listener) const {
   std::vector<EnabledStateObserver*>::const_iterator it =
       std::find(enabled_state_observer_list_.begin(),
                 enabled_state_observer_list_.end(),
                 listener);
   return it != enabled_state_observer_list_.end();
 }
 
-float TraceLog::GetBufferPercentFull() const {
+TraceLogStatus TraceLog::GetStatus() const {
   AutoLock lock(lock_);
-  return static_cast<float>(static_cast<double>(logged_events_->Size()) /
-                            logged_events_->Capacity());
+  TraceLogStatus result;
+  result.event_capacity = logged_events_->Capacity();
+  result.event_count = logged_events_->Size();
+  return result;
 }
 
 bool TraceLog::BufferIsFull() const {
   AutoLock lock(lock_);
   return logged_events_->IsFull();
 }
 
 TraceBuffer* TraceLog::CreateTraceBuffer() {
   InternalTraceOptions options = trace_options();
   if (options & kInternalRecordContinuously)
@@ skipping 961 matching lines @@
 }
 
 ScopedTraceBinaryEfficient::~ScopedTraceBinaryEfficient() {
   if (*category_group_enabled_) {
     TRACE_EVENT_API_UPDATE_TRACE_EVENT_DURATION(category_group_enabled_,
                                                 name_, event_handle_);
   }
 }
 
 }  // namespace trace_event_internal