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

content/browser/tracing/trace_message_filter.cc

Index: content/browser/tracing/trace_message_filter.cc
diff --git a/content/browser/tracing/trace_message_filter.cc b/content/browser/tracing/trace_message_filter.cc
index e74ca96caa65dc75aeaa79375748f320749e7046..895b3aab5e18d733fc2089e2116d82867cb71710 100644
--- a/content/browser/tracing/trace_message_filter.cc
+++ b/content/browser/tracing/trace_message_filter.cc
@@ -28,7 +28,7 @@ void TraceMessageFilter::OnChannelClosing() {
       OnCaptureMonitoringSnapshotAcked();
 
     if (is_awaiting_buffer_percent_full_ack_)
-      OnTraceBufferPercentFullReply(0.0f);
+      OnTraceBufferPercentFullReply(0.0f, 0);
 
     TracingControllerImpl::GetInstance()->RemoveTraceMessageFilter(this);
   }
@@ -157,11 +157,12 @@ void TraceMessageFilter::OnWatchEventMatched() {
   TracingControllerImpl::GetInstance()->OnWatchEventMatched();
 }
 
-void TraceMessageFilter::OnTraceBufferPercentFullReply(float percent_full) {
+void TraceMessageFilter::OnTraceBufferPercentFullReply(float percent_full,
+                                                       size_t buffer_usage) {
   if (is_awaiting_buffer_percent_full_ack_) {
     is_awaiting_buffer_percent_full_ack_ = false;
     TracingControllerImpl::GetInstance()->OnTraceBufferPercentFullReply(
-        this, percent_full);
+        this, percent_full, buffer_usage);
   } else {
     NOTREACHED();
   }