service worker: Remove references to non-exist WebServiceWorkerRegistration

The class seemed to be gone as a part of the Onion Soup. Remove
references to the class and update comments.

Bug: N/A
Change-Id: Ia093586c40295d09bffcf713d6156a20e96b43c5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1877489
Commit-Queue: Kenichi Ishibashi <bashi@chromium.org>
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#709316}

content/browser/service_worker/service_worker_registration_object_host.h

@@ -22,11 +22,8 @@ class ServiceWorkerContextCore;
 class ServiceWorkerVersion;
 
 // ServiceWorkerRegistrationObjectHost has a 1:1 correspondence to
-// WebServiceWorkerRegistration in the renderer process.
-// The host stays alive while the WebServiceWorkerRegistration is alive, and
-// also initiates destruction of the WebServiceWorkerRegistration once detected
-// that it's no longer needed. See the class documentation in
-// WebServiceWorkerRegistrationImpl for details.
+// blink::ServiceWorkerRegistration in the renderer process.
+// The host stays alive while the blink::ServiceWorkerRegistration is alive.
 //
 // Has a reference to the corresponding ServiceWorkerRegistration in order to
 // ensure that the registration is alive while this object host is around.

content/renderer/service_worker/service_worker_provider_context.h

@@ -57,13 +57,12 @@ FORWARD_DECLARE_TEST(ServiceWorkerProviderContextTest,
 }  // namespace service_worker_provider_context_unittest
 
 class WebServiceWorkerProviderImpl;
-class WebServiceWorkerRegistrationImpl;
 struct ServiceWorkerProviderContextDeleter;
 
 // ServiceWorkerProviderContext stores common state for "providers" for service
 // worker clients (currently WebServiceWorkerProviderImpl and
-// ServiceWorkerNetworkProviderFor{Frame,Worker}). Providers for the same
-// underlying entity hold strong references to a shared instance of this class.
+// ServiceWorkerNetworkProviderForFrame). Providers for the same underlying
+// entity hold strong references to a shared instance of this class.
 //
 // ServiceWorkerProviderContext is also a
 // blink::mojom::ServiceWorkerWorkerClientRegistry. If it's a provider for a
@@ -189,7 +188,6 @@ class CONTENT_EXPORT ServiceWorkerProviderContext
                                           ServiceWorkerProviderContextDeleter>;
   friend class service_worker_provider_context_unittest::
       ServiceWorkerProviderContextTest;
-  friend class WebServiceWorkerRegistrationImpl;
   friend struct ServiceWorkerProviderContextDeleter;
   FRIEND_TEST_ALL_PREFIXES(service_worker_provider_context_unittest::
                                ServiceWorkerProviderContextTest,