service worker: Tweak some documentation.

content/browser/service_worker/service_worker_provider_host.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_PROVIDER_HOST_H_
 #define CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_PROVIDER_HOST_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
+#include <map>
+#include <memory>
 #include <set>
+#include <string>
 #include <vector>
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "content/browser/service_worker/service_worker_registration.h"
 #include "content/common/content_export.h"
 #include "content/common/service_worker/service_worker_types.h"
 #include "content/public/common/request_context_frame_type.h"
 #include "content/public/common/request_context_type.h"
 #include "content/public/common/resource_type.h"
 
-namespace IPC {
-class Sender;
-}
-
 namespace storage {
 class BlobStorageContext;
 }
 
 namespace content {
 
 class ResourceRequestBodyImpl;
 class ServiceWorkerContextCore;
 class ServiceWorkerDispatcherHost;
 class ServiceWorkerRequestHandler;
 class ServiceWorkerVersion;
 
 // This class is the browser-process representation of a service worker
-// provider. There is a provider per document or a worker and the lifetime
-// of this object is tied to the lifetime of its document or the worker
-// in the renderer process.
-// This class holds service worker state that is scoped to an individual
-// document or a worker.
+// provider. There are two general types of providers: 1) those for a client
+// (windows, dedicated workers, or shared workers), and 2) those for hosting a
+// running service worker.
 //
-// Note this class can also host a running service worker, in which
-// case it will observe resource loads made directly by the service worker.
+// For client providers, there is a provider per document or a worker and the
+// lifetime of this object is tied to the lifetime of its document or the worker
+// in the renderer process. This class holds service worker state that is scoped
+// to an individual document or a worker.
+//
+// For providers hosting a running service worker, this class will observe
+// resource loads made directly by the service worker.
 class CONTENT_EXPORT ServiceWorkerProviderHost
     : public NON_EXPORTED_BASE(ServiceWorkerRegistration::Listener),
       public base::SupportsWeakPtr<ServiceWorkerProviderHost> {
  public:
   using GetRegistrationForReadyCallback =
       base::Callback<void(ServiceWorkerRegistration* reigstration)>;
 
   // PlzNavigate
   // Used to pre-create a ServiceWorkerProviderHost for a navigation. The
   // ServiceWorkerNetworkProvider will later be created in the renderer, should
@@ skipping 258 matching lines @@
   bool IsReadyToSendMessages() const;
   void Send(IPC::Message* message) const;
 
   // Finalizes cross-site transfers and navigation-initalized hosts.
   void FinalizeInitialization(int process_id,
                               int frame_routing_id,
                               ServiceWorkerDispatcherHost* dispatcher_host);
 
   std::string client_uuid_;
   int render_process_id_;
+
+  // See the constructor's documentation.
   int route_id_;
+
+  // For provider hosts that are hosting a running service worker, the id of the
+  // service worker thread. Otherwise, |kDocumentMainThreadId|. May be
+  // |kInvalidEmbeddedWorkerThreadId| before the hosted service worker starts
+  // up, or during cross-site transfers.
   int render_thread_id_;
+
+  // Unique within the renderer process.
   int provider_id_;
+
   ServiceWorkerProviderType provider_type_;
   FrameSecurityLevel parent_frame_security_level_;
   GURL document_url_;
   GURL topmost_frame_url_;
 
   std::vector<GURL> associated_patterns_;
   scoped_refptr<ServiceWorkerRegistration> associated_registration_;
 
   // Keyed by registration scope URL length.
   typedef std::map<size_t, scoped_refptr<ServiceWorkerRegistration>>
@@ skipping 11 matching lines @@
   bool allow_association_;
 
   std::vector<base::Closure> queued_events_;
 
   DISALLOW_COPY_AND_ASSIGN(ServiceWorkerProviderHost);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_PROVIDER_HOST_H_