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..2aeed4cc3a8c6cc45059bafd577740b35d85a86f 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);
+      OnTraceBufferUsageReply(0.0f, 0);
 
     TracingControllerImpl::GetInstance()->RemoveTraceMessageFilter(this);
   }
@@ -49,8 +49,8 @@ bool TraceMessageFilter::OnMessageReceived(const IPC::Message& message) {
                         OnMonitoringTraceDataCollected)
     IPC_MESSAGE_HANDLER(TracingHostMsg_WatchEventMatched,
                         OnWatchEventMatched)
-    IPC_MESSAGE_HANDLER(TracingHostMsg_TraceBufferPercentFullReply,
-                        OnTraceBufferPercentFullReply)
+    IPC_MESSAGE_HANDLER(TracingHostMsg_TraceBufferUsageReply,
+                        OnTraceBufferUsageReply)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
   return handled;
@@ -93,11 +93,11 @@ void TraceMessageFilter::SendCaptureMonitoringSnapshot() {
   Send(new TracingMsg_CaptureMonitoringSnapshot);
 }
 
-void TraceMessageFilter::SendGetTraceBufferPercentFull() {
+void TraceMessageFilter::SendGetTraceBufferUsage() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   DCHECK(!is_awaiting_buffer_percent_full_ack_);
   is_awaiting_buffer_percent_full_ack_ = true;
-  Send(new TracingMsg_GetTraceBufferPercentFull);
+  Send(new TracingMsg_GetTraceBufferUsage);
 }
 
 void TraceMessageFilter::SendSetWatchEvent(const std::string& category_name,
@@ -157,11 +157,13 @@ void TraceMessageFilter::OnWatchEventMatched() {
   TracingControllerImpl::GetInstance()->OnWatchEventMatched();
 }
 
-void TraceMessageFilter::OnTraceBufferPercentFullReply(float percent_full) {
+void TraceMessageFilter::OnTraceBufferUsageReply(
+    float percent_full,
+    size_t approximate_event_count) {
   if (is_awaiting_buffer_percent_full_ack_) {
     is_awaiting_buffer_percent_full_ack_ = false;
-    TracingControllerImpl::GetInstance()->OnTraceBufferPercentFullReply(
-        this, percent_full);
+    TracingControllerImpl::GetInstance()->OnTraceBufferUsageReply(
+        this, percent_full, approximate_event_count);
   } else {
     NOTREACHED();
   }