Revert of 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 "chrome/browser/prerender/prerender_handle.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 managing a prerendering request for offlining. This handles
-// all calls into the prerender stack and tracks the active prerender handle.
-class PrerenderAdapter : public prerender::PrerenderHandle::Observer {
- public:
-  // An observer of PrerenderHandle events that does not expose the handle.
-  class Observer {
-   public:
-    // Signals that the prerender has started running.
-    virtual void OnPrerenderStart() = 0;
-
-    // Signals that the prerender has had its load event.
-    virtual void OnPrerenderStopLoading() = 0;
-
-    // Signals that the prerender has had its 'DOMContentLoaded' event.
-    virtual void OnPrerenderDomContentLoaded() = 0;
-
-    // Signals that the prerender has stopped running and any retrieved
-    // WebContents (via |GetWebContents()|) have become invalidated.
-    virtual void OnPrerenderStop() = 0;
-
-   protected:
-    Observer();
-    virtual ~Observer();
-  };
-
-  explicit PrerenderAdapter(PrerenderAdapter::Observer* observer);
-  ~PrerenderAdapter() override;
-
-  // Returns whether prerendering is enabled and configured.
-  virtual bool CanPrerender() const;
-
-  // Starts prerendering |url| for offlining. There must be no active
-  // prerender request when calling this. Returns whether it was able
-  // to start the prerendering operation.
-  virtual bool StartPrerender(
-      content::BrowserContext* browser_context,
-      const GURL& url,
-      content::SessionStorageNamespace* session_storage_namespace,
-      const gfx::Size& size);
-
-  // 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 |DestroyActive()|
-  // to report when it no longer needs the web contents. The caller should
-  // watch for its |PrerenderAdapter::Observer::OnPrerenderStop()| to
-  // learn that the web contents should no longer be used.
-  virtual content::WebContents* GetWebContents() const;
-
-  // Returns the final status of prerendering.
-  virtual prerender::FinalStatus GetFinalStatus() const;
-
-  // Returns whether this adapter has an active prerender request. This
-  // adapter supports one request at a time. DestroyActive() may be used
-  // to clear an active request (which will allow StartPrerender() to be
-  // called to request a new one).
-  virtual bool IsActive() const;
-
-  // Cancels any current prerendering operation and destroys its local handle.
-  virtual void DestroyActive();
-
-  // PrerenderHandle::Observer interface:
-  void OnPrerenderStart(prerender::PrerenderHandle* handle) override;
-  void OnPrerenderStopLoading(prerender::PrerenderHandle* handle) override;
-  void OnPrerenderDomContentLoaded(prerender::PrerenderHandle* handle) override;
-  void OnPrerenderStop(prerender::PrerenderHandle* handle) override;
-
- 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_;
-
-  // Observer of active handle events. Not owned.
-  PrerenderAdapter::Observer* observer_;
-
-  DISALLOW_COPY_AND_ASSIGN(PrerenderAdapter);
-};
-
-}  // namespace offline_pages
-
-#endif  // CHROME_BROWSER_ANDROID_OFFLINE_PAGES_PRERENDER_ADAPTER_H_