Reland fast tab closure behind a flag

chrome/browser/ui/fast_unload_controller.h

Index: chrome/browser/ui/fast_unload_controller.h
diff --git a/chrome/browser/ui/fast_unload_controller.h b/chrome/browser/ui/fast_unload_controller.h
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+// 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_UI_FAST_UNLOAD_CONTROLLER_H_
+#define CHROME_BROWSER_UI_FAST_UNLOAD_CONTROLLER_H_
+
+#include <set>
+
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "base/strings/string_piece.h"
+#include "chrome/browser/ui/tabs/tab_strip_model_observer.h"
+#include "content/public/browser/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
+
+class Browser;
+class TabStripModel;
+
+namespace content {
+class NotificationSource;
+class NotifictaionDetails;
+class WebContents;
+}
+
+namespace chrome {
+// FastUnloadController manages closing tabs and windows -- especially in
+// regards to beforeunload handlers (have proceed/cancel dialogs) and
+// unload handlers (have no user interaction).
+//
+// Typical flow of closing a tab:
+//  1. Browser calls CanCloseContents().
+//     If true, browser calls contents::CloseWebContents().
+//  2. WebContents notifies us via its delegate and BeforeUnloadFired()
+//     that the beforeunload handler was run. If the user allowed the
+//     close to continue, we detached the tab and hold onto it while the
+//     close finishes.
+//
+// Typical flow of closing a window:
+//  1. BrowserView::CanClose() calls TabsNeedBeforeUnloadFired().
+//     If beforeunload/unload handlers need to run, FastUnloadController returns
+//     true and calls ProcessPendingTabs() (private method).
+//  2. For each tab with a beforeunload/unload handler, ProcessPendingTabs()
+//        calls |CoreTabHelper::OnCloseStarted()|
+//        and   |web_contents->GetRenderViewHost()->FirePageBeforeUnload()|.
+//  3. If the user allowed the close to continue, we detach all the tabs with
+//     unload handlers, remove them from the tab strip, and finish closing
+//     the tabs in the background.
+//  4. The browser gets notified that the tab strip is empty and calls
+//     CloseFrame where the empty tab strip causes the window to hide.
+//     Once the detached tabs finish, the browser calls CloseFrame again and
+//     the window is finally closed.
+//
+class FastUnloadController : public content::NotificationObserver,
+                             public TabStripModelObserver {
+ public:
+  explicit FastUnloadController(Browser* browser);
+  virtual ~FastUnloadController();
+
+  // Returns true if |contents| can be cleanly closed. When |browser_| is being
+  // closed, this function will return false to indicate |contents| should not
+  // be cleanly closed, since the fast shutdown path will just kill its
+  // renderer.
+  bool CanCloseContents(content::WebContents* contents);
+
+  // Called when a BeforeUnload handler is fired for |contents|. |proceed|
+  // indicates the user's response to the Y/N BeforeUnload handler dialog. If
+  // this parameter is false, any pending attempt to close the whole browser
+  // will be canceled. Returns true if Unload handlers should be fired. When the
+  // |browser_| is being closed, Unload handlers for any particular WebContents
+  // will not be run until every WebContents being closed has a chance to run
+  // its BeforeUnloadHandler.
+  bool BeforeUnloadFired(content::WebContents* contents, bool proceed);
+
+  bool is_attempting_to_close_browser() const {
+    return is_attempting_to_close_browser_;
+  }
+
+  // Called in response to a request to close |browser_|'s window. Returns true
+  // when there are no remaining beforeunload handlers to be run.
+  bool ShouldCloseWindow();
+
+  // Returns true if |browser_| has any tabs that have BeforeUnload handlers
+  // that have not been fired. This method is non-const because it builds a list
+  // of tabs that need their BeforeUnloadHandlers fired.
+  // TODO(beng): This seems like it could be private but it is used by
+  //             AreAllBrowsersCloseable() in application_lifetime.cc. It seems
+  //             very similar to ShouldCloseWindow() and some consolidation
+  //             could be pursued.
+  bool TabsNeedBeforeUnloadFired();
+
+  // Returns true if all tabs' beforeunload/unload events have fired.
+  bool HasCompletedUnloadProcessing() const;
+
+ private:
+  // Overridden from content::NotificationObserver:
+  virtual void Observe(int type,
+                       const content::NotificationSource& source,
+                       const content::NotificationDetails& details) OVERRIDE;
+
+  // Overridden from TabStripModelObserver:
+  virtual void TabInsertedAt(content::WebContents* contents,
+                             int index,
+                             bool foreground) OVERRIDE;
+  virtual void TabDetachedAt(content::WebContents* contents,
+                             int index) OVERRIDE;
+  virtual void TabReplacedAt(TabStripModel* tab_strip_model,
+                             content::WebContents* old_contents,
+                             content::WebContents* new_contents,
+                             int index) OVERRIDE;
+  virtual void TabStripEmpty() OVERRIDE;
+
+  void TabAttachedImpl(content::WebContents* contents);
+  void TabDetachedImpl(content::WebContents* contents);
+
+  // Detach |contents| and wait for it to finish closing.
+  // The close must be inititiated outside of this method.
+  // Returns true if it succeeds.
+  bool DetachWebContents(content::WebContents* contents);
+
+  // Processes the next tab that needs it's beforeunload/unload event fired.
+  void ProcessPendingTabs();
+
+  // Clears all the state associated with processing tabs' beforeunload/unload
+  // events since the user cancelled closing the window.
+  void CancelWindowClose();
+
+  // Cleans up state appropriately when we are trying to close the
+  // browser or close a tab in the background. We also use this in the
+  // cases where a tab crashes or hangs even if the
+  // beforeunload/unload haven't successfully fired.
+  void ClearUnloadState(content::WebContents* contents);
+
+  // Helper for |ClearUnloadState| to unwind stack before proceeding.
+  void PostTaskForProcessPendingTabs();
+
+  // Log a step of the unload processing.
+  void LogUnloadStep(const base::StringPiece& step_name,
+                     content::WebContents* contents) const;
+
+  Browser* browser_;
+
+  content::NotificationRegistrar registrar_;
+
+  typedef std::set<content::WebContents*> WebContentsSet;
+
+  // Tracks tabs that need their beforeunload event started.
+  // Only gets populated when we try to close the browser.
+  WebContentsSet tabs_needing_before_unload_;
+
+  // Tracks the tab that needs its beforeunload event result.
+  // Only gets populated when we try to close the browser.
+  content::WebContents* tab_needing_before_unload_ack_;
+
+  // Tracks tabs that need their unload event started.
+  // Only gets populated when we try to close the browser.
+  WebContentsSet tabs_needing_unload_;
+
+  // Tracks tabs that need to finish running their unload event.
+  // Populated both when closing individual tabs and when closing the browser.
+  WebContentsSet tabs_needing_unload_ack_;
+
+  // Whether we are processing the beforeunload and unload events of each tab
+  // in preparation for closing the browser. FastUnloadController owns this
+  // state rather than Browser because unload handlers are the only reason that
+  // a Browser window isn't just immediately closed.
+  bool is_attempting_to_close_browser_;
+
+  // Manage tabs with beforeunload/unload handlers that close detached.
+  class DetachedWebContentsDelegate;
+  scoped_ptr<DetachedWebContentsDelegate> detached_delegate_;
+
+  base::WeakPtrFactory<FastUnloadController> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(FastUnloadController);
+};
+
+}  // namespace chrome
+
+#endif  // CHROME_BROWSER_UI_FAST_UNLOAD_CONTROLLER_H_