Add basic browser test for EmbeddedWorker/ServiceWorker

content/browser/service_worker/embedded_worker_instance.h

Index: content/browser/service_worker/embedded_worker_instance.h
diff --git a/content/browser/service_worker/embedded_worker_instance.h b/content/browser/service_worker/embedded_worker_instance.h
index 5a992a2d4ff7528f0793fb1f0878b7cb553871c7..fcc2c3481996bc273182379c35b2a4e51ab476ae 100644
--- a/content/browser/service_worker/embedded_worker_instance.h
+++ b/content/browser/service_worker/embedded_worker_instance.h
@@ -12,6 +12,7 @@
 #include "base/gtest_prod_util.h"
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
+#include "base/observer_list.h"
 #include "content/common/content_export.h"
 
 class GURL;
@@ -33,6 +34,13 @@ class CONTENT_EXPORT EmbeddedWorkerInstance {
     STOPPING,
   };
 
+  class Observer {
+   public:
+    virtual ~Observer() {}
+    virtual void OnStarted() = 0;
+    virtual void OnStopped() = 0;
+  };
+
   ~EmbeddedWorkerInstance();
 
   // Starts the worker. It is invalid to call this when the worker is
@@ -63,6 +71,9 @@ class CONTENT_EXPORT EmbeddedWorkerInstance {
   int process_id() const { return process_id_; }
   int thread_id() const { return thread_id_; }
 
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
  private:
   friend class EmbeddedWorkerRegistry;
   FRIEND_TEST_ALL_PREFIXES(EmbeddedWorkerInstanceTest, StartAndStop);
@@ -99,6 +110,7 @@ class CONTENT_EXPORT EmbeddedWorkerInstance {
   int thread_id_;
 
   ProcessRefMap process_refs_;
+  ObserverList<Observer> observer_list_;
 
   DISALLOW_COPY_AND_ASSIGN(EmbeddedWorkerInstance);
 };