Add ref count to service workers for extension API.

content/public/browser/service_worker_context.h

Index: content/public/browser/service_worker_context.h
diff --git a/content/public/browser/service_worker_context.h b/content/public/browser/service_worker_context.h
index 47f355c734ae46b1a5e17b04968f898a526901c0..c095f9d1314c7fe028441bb19479c2f73d4fc99e 100644
--- a/content/public/browser/service_worker_context.h
+++ b/content/public/browser/service_worker_context.h
@@ -23,15 +23,18 @@ class ServiceWorkerContext {
  public:
   // https://rawgithub.com/slightlyoff/ServiceWorker/master/spec/service_worker/index.html#url-scope:
   // roughly, must be of the form "<origin>/<path>/*".
-  typedef GURL Scope;
+  using Scope = GURL;
 
-  typedef base::Callback<void(bool success)> ResultCallback;
+  using ResultCallback = base::Callback<void(bool success)>;
 
-  typedef base::Callback<void(const std::vector<ServiceWorkerUsageInfo>&
-                                  usage_info)> GetUsageInfoCallback;
+  using GetUsageInfoCallback = base::Callback<void(
+      const std::vector<ServiceWorkerUsageInfo>& usage_info)>;
 
-  typedef base::Callback<void(bool has_service_worker)>
-      CheckHasServiceWorkerCallback;
+  using CheckHasServiceWorkerCallback =
+      base::Callback<void(bool has_service_worker)>;
+
+  using CountExternalRequestsCallback =
+      base::Callback<void(size_t external_request_count)>;
 
   // Registers the header name which should not be passed to the ServiceWorker.
   // Must be called from the IO thread.
@@ -60,6 +63,21 @@ class ServiceWorkerContext {
                                      const GURL& script_url,
                                      const ResultCallback& callback) = 0;
 
+  // Mechanism for embedder to increment/decrement ref count of a service
+  // worker.
+  // Embedders can call StartingExternalRequest() while it is performing some
+  // work with the worker. The worker is considered to be working until embedder
+  // calls FinishedExternalRequest(). This ensures that content/ does not
+  // shut the worker down while embedder is expecting the worker to be kept
+  // alive.
+  //
+  // Must be called from the IO thread. Returns whether or not changing the ref
+  // count succeeded.
+  virtual bool StartingExternalRequest(int64_t service_worker_version_id,
+                                       const std::string& request_uuid) = 0;
+  virtual bool FinishedExternalRequest(int64_t service_worker_version_id,
+                                       const std::string& request_uuid) = 0;
+
   // Equivalent to calling navigator.serviceWorker.unregister(pattern) from a
   // renderer, except that |pattern| is an absolute URL instead of relative to
   // some current origin.  |callback| is passed true when the JS promise is
@@ -96,6 +114,12 @@ class ServiceWorkerContext {
       const GURL& other_url,
       const CheckHasServiceWorkerCallback& callback) = 0;
 
+  // Returns the pending external request count for the worker with the
+  // specified |origin| via |callback|.
+  virtual void CountExternalRequestsForTest(
+      const GURL& origin,
+      const CountExternalRequestsCallback& callback) = 0;
+
   // Stops all running workers on the given |origin|.
   //
   // This function can be called from any thread.