Report trace buffer usage as number of events, not only percentage

base/debug/trace_event_impl.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_DEBUG_TRACE_EVENT_IMPL_H_
 #define BASE_DEBUG_TRACE_EVENT_IMPL_H_
 
 #include <stack>
 #include <string>
@@ skipping 477 matching lines @@
     virtual void OnTraceLogEnabled() = 0;
 
     // Called just after the tracing system disables, outside of the |lock_|.
     // TraceLog::IsEnabled() is false at this point.
     virtual void OnTraceLogDisabled() = 0;
   };
   void AddEnabledStateObserver(EnabledStateObserver* listener);
   void RemoveEnabledStateObserver(EnabledStateObserver* listener);
   bool HasEnabledStateObserver(EnabledStateObserver* listener) const;
 
-  float GetBufferPercentFull() const;
+  struct BufferUsage {
+    float percent_full;
+    size_t approximate_event_count;
+  };
+  BufferUsage GetBufferUsage() const;
   bool BufferIsFull() const;
 
   // Not using base::Callback because of its limited by 7 parameters.
   // Also, using primitive type allows directly passing callback from WebCore.
   // WARNING: It is possible for the previously set callback to be called
   // after a call to SetEventCallbackEnabled() that replaces or a call to
   // SetEventCallbackDisabled() that disables the callback.
   // This callback may be invoked on any thread.
   // For TRACE_EVENT_PHASE_COMPLETE events, the client will still receive pairs
   // of TRACE_EVENT_PHASE_BEGIN and TRACE_EVENT_PHASE_END events to keep the
@@ skipping 87 matching lines @@
   int process_id() const { return process_id_; }
 
   // Exposed for unittesting:
 
   void WaitSamplingEventForTesting();
 
   // Allows deleting our singleton instance.
   static void DeleteForTesting();
 
   // Allow tests to inspect TraceEvents.
-  size_t GetEventsSize() const { return logged_events_->Size(); }
   TraceEvent* GetEventByHandle(TraceEventHandle handle);
 
   void SetProcessID(int process_id);
 
   // Process sort indices, if set, override the order of a process will appear
   // relative to other processes in the trace viewer. Processes are sorted first
   // on their sort index, ascending, then by their name, and then tid.
   void SetProcessSortIndex(int sort_index);
 
   // Sets the name of the process.
@@ skipping 182 matching lines @@
   scoped_refptr<MessageLoopProxy> flush_message_loop_proxy_;
   subtle::AtomicWord generation_;
 
   DISALLOW_COPY_AND_ASSIGN(TraceLog);
 };
 
 }  // namespace debug
 }  // namespace base
 
 #endif  // BASE_DEBUG_TRACE_EVENT_IMPL_H_