Add an abstraction for a job in the AppCacheRequestHandler class.

content/browser/appcache/appcache_job.h

+// Copyright (c) 2017 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_APPCACHE_APPCACHE_JOB_H_
+#define CONTENT_BROWSER_APPCACHE_APPCACHE_JOB_H_
+
+#include <memory>
+
+#include "base/logging.h"
+#include "base/memory/weak_ptr.h"
+#include "base/strings/string16.h"
+#include "base/threading/non_thread_safe.h"
+#include "content/common/content_export.h"
+#include "url/gurl.h"
+
+namespace net {
+class NetworkDelegate;
+class URLRequestJob;
+}
+
+namespace content {
+
+class AppCacheEntry;
+class AppCacheHost;
+class AppCacheRequest;
+class AppCacheStorage;
+class URLRequestJob;
+
+// Interface for an AppCache job. Subclasses implement this interface to

[jam, 2017/05/05 23:15:25]

nit: can you describe what the purpose of this interface is? i.e. it's used to
send data stored in appcache to the networking code

[ananta, 2017/05/06 03:01:35]

Done.

+// wrap custom job objects like URLRequestJob, URLLoaderJob, etc to ensure that
+// these dependencies stay out of the AppCache code.
+class CONTENT_EXPORT AppCacheJob
+    : NON_EXPORTED_BASE(public base::NonThreadSafe),
+      public base::SupportsWeakPtr<AppCacheJob> {

[jam, 2017/05/05 23:15:25]

nit: don't need to derive from SupportsWeakPtr since it already has a
GetWeakPtr()

[ananta, 2017/05/06 03:01:34]

Unfortunately we need this as the AppCacheURLRequestJob class uses the weakptr
to post tasks within
itself. This ensures that we get a casted weakptr.

[jam, 2017/05/08 14:03:12]

AppCacheURLRequestJob used to call weak_factory_.GetWeakPtr(). You changed it to
StaticAsWeakPtr(this).

but it can also be written as GetWeakPtr(), and then you can remove the base
class from the interface

+ public:
+  // Callback that will be invoked before the request is restarted. The caller
+  // can use this opportunity to grab state from the job to determine how it
+  // should behave when the request is restarted.
+  // TODO(ananta)
+  // This applies only to the URLRequestJob at the moment. Look into taking
+  // this knowledge out of this class.
+  using OnPrepareToRestartCallback = base::Closure;
+
+  // Controls which job gets created.
+  enum class kJobType {
+    URL_REQUEST_JOB,  // The regular URLRequestJob.
+    URL_LOADER_JOB,   // The URLLoader job used by the mojo network service.
+  };
+
+  // Factory function to create the AppCacheJob instance for the |request|
+  // passed in. The |job_type| parameter controls the type of job which is
+  // created.
+  static std::unique_ptr<AppCacheJob> Create(
+      kJobType job_type,
+      bool is_main_resource,
+      AppCacheHost* host,
+      AppCacheStorage* storage,
+      AppCacheRequest* request,
+      net::NetworkDelegate* network_delegate,
+      const OnPrepareToRestartCallback& restart_callback);
+
+  virtual ~AppCacheJob();
+
+  // Kills the job.
+  virtual void Kill() = 0;
+
+  // Returns true if the job was started.
+  virtual bool IsStarted() const = 0;
+
+  // Returns true if the job is waiting for instructions.
+  virtual bool IsWaiting() const = 0;
+
+  // Returns true if the job is delivering a response from the cache.
+  virtual bool IsDeliveringAppCacheResponse() const = 0;
+
+  // Returns true if the job is delivering a response from the network.
+  virtual bool IsDeliveringNetworkResponse() const = 0;
+
+  // Returns true if the job is delivering an error response.
+  virtual bool IsDeliveringErrorResponse() const = 0;
+
+  // Returns true if the cache entry was not found in the cache.
+  virtual bool IsCacheEntryNotFound() const = 0;
+
+  // Informs the job of what response it should deliver. Only one of these
+  // methods should be called, and only once per job. A job will sit idle and
+  // wait indefinitely until one of the deliver methods is called.
+  virtual void DeliverAppCachedResponse(const GURL& manifest_url,
+                                        int64_t cache_id,
+                                        const AppCacheEntry& entry,
+                                        bool is_fallback) = 0;
+
+  // Informs the job that it should deliver the response from the network. This
+  // is generally controlled by the entries in the manifest file.
+  virtual void DeliverNetworkResponse() = 0;
+
+  // Informs the job that it should deliver an error response.
+  virtual void DeliverErrorResponse() = 0;
+
+  // Returns a weak pointer reference to the job.
+  virtual base::WeakPtr<AppCacheJob> GetWeakPtr();
+
+  // Returns the URL of the job.
+  virtual const GURL& GetURL() const = 0;
+
+  // Returns the underlying URLRequestJob if any. This only applies to
+  // AppCaches loaded via the URLRequest mechanism.
+  virtual net::URLRequestJob* AsURLRequestJob();
+
+ protected:
+  AppCacheJob();
+
+  base::WeakPtrFactory<AppCacheJob> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(AppCacheJob);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_APPCACHE_APPCACHE_JOB_H_