Add UMA for how long service workers run for.

content/browser/service_worker/embedded_worker_instance.h

 // Copyright 2013 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 CONTENT_BROWSER_SERVICE_WORKER_EMBEDDED_WORKER_INSTANCE_H_
 #define CONTENT_BROWSER_SERVICE_WORKER_EMBEDDED_WORKER_INSTANCE_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 127 matching lines @@
   int process_id() const;
   int thread_id() const { return thread_id_; }
   // This should be called only when the worker instance has a valid process,
   // that is, when |process_id()| returns a valid process id.
   bool is_new_process() const;
   int worker_devtools_agent_route_id() const;
 
   void AddListener(Listener* listener);
   void RemoveListener(Listener* listener);
 
-  void set_devtools_attached(bool attached) { devtools_attached_ = attached; }
+  void SetDevToolsAttached(bool attached);
   bool devtools_attached() const { return devtools_attached_; }
 
   bool network_accessed_for_script() const {
     return network_accessed_for_script_;
   }
 
   ServiceWorkerMetrics::StartSituation start_situation() const {
     DCHECK(status() == EmbeddedWorkerStatus::STARTING ||
            status() == EmbeddedWorkerStatus::RUNNING);
     return start_situation_;
@@ skipping 168 matching lines @@
   base::TimeTicks step_time_;
 
   base::WeakPtrFactory<EmbeddedWorkerInstance> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(EmbeddedWorkerInstance);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_SERVICE_WORKER_EMBEDDED_WORKER_INSTANCE_H_