Instant: Use only one hidden WebContents per profile.

chrome/browser/instant/instant_preloader.h

+// Copyright 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_INSTANT_INSTANT_PRELOADER_H_
+#define CHROME_BROWSER_INSTANT_INSTANT_PRELOADER_H_
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "base/gtest_prod_util.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/timer.h"
+#include "chrome/browser/instant/instant_page.h"
+#include "chrome/browser/instant/instant_service_observer.h"
+#include "chrome/browser/instant/instant_web_contents_container.h"
+
+class InstantService;
+
+namespace content {
+class WebContents;
+}
+
+// InstantPreloader maintains a hidden WebContents into which it loads the
+// default search engine's Instant URL. It is owned by InstantService.
+class InstantPreloader : public InstantPage::Delegate,
+                         public InstantServiceObserver,
+                         public InstantWebContentsContainer {
+ public:
+  explicit InstantPreloader(InstantService* service);
+  virtual ~InstantPreloader();
+
+  // Returns whether the |contents_| is known to support the Instant API.
+  bool supports_instant() const { return page_.supports_instant(); }
+
+  // Creates a new |contents_| and loads the Instant URL into it. If |contents_|
+  // is already valid, does nothing.
+  void InitContents();
+
+  // Gives up |contents_| to the caller, and creates a new one in its place.
+  scoped_ptr<content::WebContents> ReleaseContents();
+
+ private:
+  FRIEND_TEST_ALL_PREFIXES(InstantTest, InstantPreloaderRefresh);
+
+  // Overridden from InstantPage::Delegate:
+  virtual void RenderViewGone(const content::WebContents* contents) OVERRIDE;
+  virtual void InitSearchBox(const content::WebContents* contents) OVERRIDE;
+  virtual void InstantSupportDetermined(
+      const content::WebContents* contents) OVERRIDE;
+  virtual void SetSuggestion(const content::WebContents* contents,
+                             const InstantSuggestion& suggestion) OVERRIDE;
+  virtual void NavigateToURL(const content::WebContents* contents,
+                             const GURL& url,
+                             content::PageTransition transition,
+                             WindowOpenDisposition disposition) OVERRIDE;
+  virtual void ShowOverlay(const content::WebContents* contents,
+                           int height,
+                           InstantSizeUnits height_units) OVERRIDE;
+  virtual void SetFocusState(const content::WebContents* contents,
+                             OmniboxFocusState focus_state) OVERRIDE;
+  virtual void DeleteMostVisitedItem(const content::WebContents* contents,
+                                     const GURL& url) OVERRIDE;
+  virtual void UndoMostVisitedItemDeletion(const content::WebContents* contents,
+                                           const GURL& url) OVERRIDE;
+  virtual void UndoAllMostVisitedItemDeletions(
+        const content::WebContents* contents) OVERRIDE;
+
+  // Overridden from InstantServiceObserver:
+  virtual void InstantStatusChanged() OVERRIDE;
+  virtual void ThemeInfoChanged() OVERRIDE;
+  virtual void MostVisitedItemsChanged() OVERRIDE;
+
+  // Overridden from InstantWebContentsContainer:
+  virtual void CloseContents(content::WebContents* source) OVERRIDE;
+  virtual void TearDownContents() OVERRIDE;
+
+  void DeleteContents();
+  void ReloadContents();
+
+  InstantService* const service_;
+  base::OneShotTimer<InstantPreloader> stale_page_timer_;
+
+  DISALLOW_COPY_AND_ASSIGN(InstantPreloader);
+};
+
+#endif  // CHROME_BROWSER_INSTANT_INSTANT_PRELOADER_H_