Document confusing threading requirements in ServiceWorkerContext(Wrapper).

content/browser/service_worker/service_worker_context_wrapper.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_SERVICE_WORKER_CONTEXT_WRAPPER_H_
 #define CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_CONTEXT_WRAPPER_H_
 
 #include <stdint.h>
 
 #include <vector>
@@ skipping 84 matching lines @@
   void GetAllOriginsInfo(const GetUsageInfoCallback& callback) override;
   void DeleteForOrigin(const GURL& origin,
                        const ResultCallback& callback) override;
   void CheckHasServiceWorker(
       const GURL& url,
       const GURL& other_url,
       const CheckHasServiceWorkerCallback& callback) override;
   void StopAllServiceWorkersForOrigin(const GURL& origin) override;
   void ClearAllServiceWorkersForTest(const base::Closure& callback) override;
 
+  // These methods must only be called from the IO thread.
   ServiceWorkerRegistration* GetLiveRegistration(int64_t registration_id);
   ServiceWorkerVersion* GetLiveVersion(int64_t version_id);
   std::vector<ServiceWorkerRegistrationInfo> GetAllLiveRegistrationInfo();
   std::vector<ServiceWorkerVersionInfo> GetAllLiveVersionInfo();
 
+  // Must be called from the IO thread.
   void HasMainFrameProviderHost(const GURL& origin,
                                 const BoolCallback& callback) const;
 
   // Returns the registration whose scope longest matches |document_url|. It is
   // guaranteed that the returned registration has the activated worker.
   //
   //  - If the registration is not found, returns ERROR_NOT_FOUND.
   //  - If the registration has neither the waiting version nor the active
   //    version, returns ERROR_NOT_FOUND.
   //  - If the registration does not have the active version but has the waiting
   //    version, activates the waiting version and runs |callback| when it is
   //    activated.
+  //
+  // Must be called from the IO thread.
   void FindReadyRegistrationForDocument(
       const GURL& document_url,
       const FindRegistrationCallback& callback);
 
   // Returns the registration for |registration_id|. It is guaranteed that the
   // returned registration has the activated worker.
   //
   //  - If the registration is not found, returns ERROR_NOT_FOUND.
   //  - If the registration has neither the waiting version nor the active
   //    version, returns ERROR_NOT_FOUND.
   //  - If the registration does not have the active version but has the waiting
   //    version, activates the waiting version and runs |callback| when it is
   //    activated.
+  //
+  // Must be called from the IO thread.
   void FindReadyRegistrationForId(int64_t registration_id,
                                   const GURL& origin,
                                   const FindRegistrationCallback& callback);
 
+  // All these methods must be called from the IO thread.
   void GetAllRegistrations(const GetRegistrationsInfosCallback& callback);
   void GetRegistrationUserData(int64_t registration_id,
                                const std::string& key,
                                const GetUserDataCallback& callback);
   void StoreRegistrationUserData(int64_t registration_id,
                                  const GURL& origin,
                                  const std::string& key,
                                  const std::string& data,
                                  const StatusCallback& callback);
   void ClearRegistrationUserData(int64_t registration_id,
                                  const std::string& key,
                                  const StatusCallback& callback);
   void GetUserDataForAllRegistrations(
       const std::string& key,
       const GetUserDataForAllRegistrationsCallback& callback);
 
+  // This function can be called from any thread, but the callback will always
+  // be called on the UI thread.
   void StartServiceWorker(const GURL& pattern, const StatusCallback& callback);
+
+  // These methods can be called from any thread.
   void UpdateRegistration(const GURL& pattern);
   void SetForceUpdateOnPageLoad(int64_t registration_id,
                                 bool force_update_on_page_load);
   void AddObserver(ServiceWorkerContextObserver* observer);
   void RemoveObserver(ServiceWorkerContextObserver* observer);
 
   bool is_incognito() const { return is_incognito_; }
 
+  // Must be called from the IO thread.
   bool OriginHasForeignFetchRegistrations(const GURL& origin);
 
  private:
   friend class BackgroundSyncManagerTest;
   friend class base::RefCountedThreadSafe<ServiceWorkerContextWrapper>;
   friend class EmbeddedWorkerTestHelper;
   friend class EmbeddedWorkerBrowserTest;
   friend class ServiceWorkerDispatcherHost;
   friend class ServiceWorkerInternalsUI;
   friend class ServiceWorkerNavigationHandleCore;
@@ skipping 53 matching lines @@
 
   // The ResourceContext associated with this context.
   ResourceContext* resource_context_;
 
   DISALLOW_COPY_AND_ASSIGN(ServiceWorkerContextWrapper);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_CONTEXT_WRAPPER_H_