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

content/browser/devtools/protocol/tracing_handler.cc

 // Copyright 2014 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 "content/browser/devtools/protocol/tracing_handler.h"
 
 #include <cmath>
 
 #include "base/bind.h"
 #include "base/debug/trace_event_impl.h"
@@ skipping 124 matching lines @@
                  weak_factory_.GetWeakPtr(),
                  command));
   return command->AsyncResponsePromise();
 }
 
 void TracingHandler::OnRecordingEnabled(
     scoped_refptr<DevToolsProtocol::Command> command) {
   client_->SendStartResponse(command, StartResponse::Create());
 }
 
-void TracingHandler::OnBufferUsage(float usage) {
-  client_->BufferUsage(BufferUsageParams::Create()->set_value(usage));
+void TracingHandler::OnBufferUsage(float percent_full,
+                                   size_t approximate_event_count) {
+  client_->BufferUsage(BufferUsageParams::Create()->set_value(percent_full));

[nduca, 2014/11/14 18:11:16]

i think you're changing the protocol response to be a dict instead of an objct
here? or are you adding a field? if a field name changed, we need to update
tracing ui and telemetry, I think...

[yurys, 2014/11/17 09:10:01]

I'm not changing the event here. My plan was to add a new field for the event
count and rename value field to percentFull. This should be done in several
steps to keep exiting code working. caseq told me that Telemetry doesn't depend
on this event and I thought that tracing uses tracing_ui.cc as backend. I will
double check but it seems that Telemetry in fact doesn't depend on this event.
It is used by chromedriver though and I see about_tracing.js references it. Is
the later needed when running tracing via remote debugger?

 }
 
 void TracingHandler::OnCategoriesReceived(
     scoped_refptr<DevToolsProtocol::Command> command,
     const std::set<std::string>& category_set) {
   std::vector<std::string> categories;
   for (const std::string& category : category_set)
     categories.push_back(category);
   client_->SendGetCategoriesResponse(command,
       GetCategoriesResponse::Create()->set_categories(categories));
@@ skipping 25 matching lines @@
 
 void TracingHandler::SetupTimer(double usage_reporting_interval) {
   if (usage_reporting_interval == 0) return;
 
   if (usage_reporting_interval < kMinimumReportingInterval)
       usage_reporting_interval = kMinimumReportingInterval;
 
   base::TimeDelta interval = base::TimeDelta::FromMilliseconds(
       std::ceil(usage_reporting_interval));
   buffer_usage_poll_timer_.reset(new base::Timer(
-      FROM_HERE,
-      interval,
-      base::Bind(
-          base::IgnoreResult(&TracingController::GetTraceBufferPercentFull),
-          base::Unretained(TracingController::GetInstance()),
-          base::Bind(&TracingHandler::OnBufferUsage,
-                     weak_factory_.GetWeakPtr())),
+      FROM_HERE, interval,
+      base::Bind(base::IgnoreResult(&TracingController::GetTraceBufferUsage),
+                 base::Unretained(TracingController::GetInstance()),
+                 base::Bind(&TracingHandler::OnBufferUsage,
+                            weak_factory_.GetWeakPtr())),
       true));
   buffer_usage_poll_timer_->Reset();
 }
 
 void TracingHandler::DisableRecording(bool abort) {
   is_recording_ = false;
   buffer_usage_poll_timer_.reset();
   TracingController::GetInstance()->DisableRecording(
       abort ? nullptr : new DevToolsTraceSinkProxy(weak_factory_.GetWeakPtr()));
 }
 
 }  // namespace tracing
 }  // namespace devtools
 }  // namespace content