components/tracing/common/background_tracing_agent.mojom

// Copyright 2019 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.

module tracing.mojom;

// This interface is used to receive callbacks from BackgroundTracingAgent.
interface BackgroundTracingAgentClient {
  OnInitialized();
  OnTriggerBackgroundTrace(string histogram_name);
  OnAbortBackgroundTrace();
};

// This interface is used to allow clients (the browser process) to monitor for
// specific metrics being hit and control when to start/stop tracing in
// response. How metrics are communicated b/w processes is not covered here.
interface BackgroundTracingAgent {
  // Call this method to begin reporting metrics corresponding to the named
  // histogram. Lower and upper bound values constrain what data is reported.
  // This results in OnTriggerBackgroundTrace callbacks (multiple if |repeat|
  // is set to true). If a histogram event does not match and |repeat| is
  // false, then OnAbortBackgroundTrace is called.
  SetUMACallback(string histogram_name,
                 int32 histogram_lower_value,
                 int32 histogram_upper_value,
                 bool repeat);

  // Call this method to stop reporting metrics corresponding to the named
  // histogram.
  ClearUMACallback(string histogram_name);
};

// This interface is used to construct a BackgroundTracingAgent.
interface BackgroundTracingAgentProvider {
  // Results in an OnInitialized callback to |client|.
  Create(uint64 tracing_process_id,
         pending_remote<BackgroundTracingAgentClient> client,
         pending_receiver<BackgroundTracingAgent> agent);
};