PrerenderingLoader initial integration with PrerenderManager/PrerenderHandle

chrome/browser/android/offline_pages/prerender_adapter.h

+// Copyright 2016 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 CHROME_BROWSER_ANDROID_OFFLINE_PAGES_PRERENDER_ADAPTER_H_
+#define CHROME_BROWSER_ANDROID_OFFLINE_PAGES_PRERENDER_ADAPTER_H_
+
+#include <memory>
+
+#include "base/callback.h"
+#include "chrome/browser/prerender/prerender_handle.h"
+#include "chrome/browser/prerender/prerender_manager.h"
+#include "components/offline_pages/background/offliner.h"
+
+class GURL;
+
+namespace content {
+class BrowserContext;
+class WebContents;
+class SessionStorageNamespace;
+}  // namespace content
+
+namespace gfx {
+class Size;
+}  // namespace gfx
+
+namespace offline_pages {
+
+// An adapter for making calls into the prerender stack for managing an
+// prerendering request for offlining (ORIGIN_OFFLINE). This provides virtual
+// methods that may be overridden or mocked to allow for unit testing.
+class PrerenderAdapter {

[pasko, 2016/05/12 19:10:07]

looks closer in meaning to something like PrerenderHandleAdapter

[dougarnett, 2016/05/13 00:00:24]

It has ended up close to that with just 2 PrerenderManager calls. But from the
point of view of the Loader it is taking care of all of the calls to the
prerender:: namespace so I'd rather not tie its name specifically to the Handle
.... unless we refactor from here.

+ public:
+  PrerenderAdapter();
+  virtual ~PrerenderAdapter();
+
+  // Returns whether prerendering is enabled and configured.
+  virtual bool CanPrerender() const;
+
+  // Requests prerendering of |url| for offlining.
+  virtual bool AddPrerenderForOffline(
+      content::BrowserContext* browser_context,
+      const GURL& url,
+      content::SessionStorageNamespace* session_storage_namespace,
+      const gfx::Size& size);
+
+  // Sets an observer on prerendering events.
+  virtual void SetObserver(prerender::PrerenderHandle::Observer* observer);
+
+  // Returns whether actively prerendering.
+  virtual bool IsPrerendering() const;
+
+  // Reports that prerendering should be canceled.
+  virtual void OnCancel();
+
+  // Returns a pointer to the prerendered WebContents. This should only be
+  // called once prerendering observer events indicate content is loaded.
+  // It may be used for snapshotting the page. The caller does NOT get
+  // ownership on the contents and must call PrerenderingLoader::StopLoading()
+  // to report when it no longer needs the contents.
+  virtual content::WebContents* GetWebContents() const;
+
+  // Returns the final status of prerendering.
+  virtual prerender::FinalStatus GetFinalStatus() const;
+
+  // Returns whether there is an active prerendering.
+  virtual bool IsActive() const;
+
+  // Returns whether there is an active prerendering associated with
+  // the |handle|. This may be used to confirm that an observed prerender
+  // event for |handle| applies to the active prerendering.
+  virtual bool IsActive(prerender::PrerenderHandle* handle) const;

[pasko, 2016/05/12 19:10:07]

would handle->IsPrerendering() be sufficient to replace this method?

[dougarnett, 2016/05/13 00:00:24]

Maybe for IsActive() which is worried about whether we still have a handle or
not while PrerenderHandler::IsPrerendering() is worried about whether the handle
is still connected to the PrerenderManager it seems.

But this one with Handle arg is trying to guard against a callback from a
previous operation being used - not sure if this is a real concern though yet.

+
+  // Destroys and clears any current prerendering operation and state.
+  virtual void DestroyActive();
+
+ private:
+  // At most one prerender request may be active for this adapter and this
+  // holds its handle if one is active.
+  std::unique_ptr<prerender::PrerenderHandle> active_handle_;
+};
+
+}  // namespace offline_pages
+
+#endif  // CHROME_BROWSER_ANDROID_OFFLINE_PAGES_PRERENDER_ADAPTER_H_