Handle interface to prerenders.

chrome/browser/prerender/prerender_handle.h

+// Copyright (c) 2012 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_PRERENDER_PRERENDER_HANDLE_H_
+#define CHROME_BROWSER_PRERENDER_PRERENDER_HANDLE_H_
+
+#include "base/basictypes.h"
+#include "base/memory/weak_ptr.h"
+#include "base/threading/non_thread_safe.h"
+#include "chrome/browser/prerender/prerender_manager.h"
+
+class GURL;
+
+namespace content {
+class SessionStorageNamespace;
+}
+
+namespace prerender {
+
+class PrerenderContents;
+
+// A class representing a running prerender to a client of the PrerenderManager.
+// Methods on PrerenderManager which start prerenders return a caller-owned
+// PrerenderHandle* to the client (or NULL if they are unable to start a
+// prerender). Because the PrerenderManager can stop running prerenders at any
+// time, callers may wish to check PrerenderHandle::IsValid() before operating
+// on their prerenders.
+class PrerenderHandle : public base::NonThreadSafe {
+ public:
+  // Before calling the destructor, the caller must invalidate the handle by
+  // calling either OnNavigateAway or OnCancel.
+  ~PrerenderHandle();
+
+  // The launcher is navigating away from the context that launched this
+  // prerender. The prerender will likely stay alive briefly though, in case we
+  // are going through a redirect chain that will target it. This call
+  // invalidates the handle. If the prerender handle is already invalid, this
+  // call does nothing.
+  void OnNavigateAway();
+
+  // The launcher has taken explicit action to remove this prerender (for
+  // instance, removing a link element from a document). This call invalidates
+  // the handle. If the prerender handle is already invalid, this call does
+  // nothing.
+  void OnCancel();
+
+  // True if the prerender handle is still connected to a (pending or running)
+  // prerender. Handles can become invalid through explicit requests by the
+  // client, such as calling OnCancel() or OnNavigateAway(), and handles
+  // also become invalid when the PrerenderManager cancels prerenders.
+  bool IsValid() const;
+
+  // True if this prerender was launched by a page that was itself being
+  // prerendered, and so has not yet been started.
+  bool IsPending() const;
+
+  // True if this prerender is currently active.
+  bool IsPrerendering() const;
+
+  // True if we started a prerender, and it has finished loading.
+  bool IsFinishedLoading() const;
+
+ private:
+  friend class PrerenderManager;
+
+  explicit PrerenderHandle(PrerenderManager::PrerenderData* prerender_data);
+
+  void SwapPrerenderDataWith(PrerenderHandle* other_prerender_handle);
+
+  base::WeakPtr<PrerenderManager::PrerenderData> prerender_data_;
+  base::WeakPtrFactory<PrerenderHandle> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(PrerenderHandle);
+};
+
+}  // namespace prerender
+
+#endif  // CHROME_BROWSER_PRERENDER_PRERENDER_HANDLE_H_