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/unload_controller.h b/chrome/browser/ui/fast_unload_controller.h
similarity index 91%
copy from chrome/browser/ui/unload_controller.h
copy to chrome/browser/ui/fast_unload_controller.h
index 265e658643c88267e154d4d83431aabdda24f682..173aca4db1cf80883868051ddf9183287a4fa707 100644
--- a/chrome/browser/ui/unload_controller.h
+++ b/chrome/browser/ui/fast_unload_controller.h
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef CHROME_BROWSER_UI_UNLOAD_CONTROLLER_H_
-#define CHROME_BROWSER_UI_UNLOAD_CONTROLLER_H_
+#ifndef CHROME_BROWSER_UI_FAST_UNLOAD_CONTROLLER_H_
+#define CHROME_BROWSER_UI_FAST_UNLOAD_CONTROLLER_H_
 
 #include <set>
 
@@ -24,7 +24,7 @@ class WebContents;
 }
 
 namespace chrome {
-// UnloadController manages closing tabs and windows -- especially in
+// FastUnloadController manages closing tabs and windows -- especially in
 // regards to beforeunload handlers (have proceed/cancel dialogs) and
 // unload handlers (have no user interaction).
 //
@@ -38,7 +38,7 @@ namespace chrome {
 //
 // Typical flow of closing a window:
 //  1. BrowserView::CanClose() calls TabsNeedBeforeUnloadFired().
-//     If beforeunload/unload handlers need to run, UnloadController returns
+//     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()|
@@ -51,11 +51,11 @@ namespace chrome {
 //     Once the detached tabs finish, the browser calls CloseFrame again and
 //     the window is finally closed.
 //
-class UnloadController : public content::NotificationObserver,
+class FastUnloadController : public content::NotificationObserver,
                              public TabStripModelObserver {
  public:
-  explicit UnloadController(Browser* browser);
-  virtual ~UnloadController();
+  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
@@ -161,7 +161,7 @@ class UnloadController : public content::NotificationObserver,
   WebContentsSet tabs_needing_unload_ack_;
 
   // Whether we are processing the beforeunload and unload events of each tab
-  // in preparation for closing the browser. UnloadController owns this
+  // 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_;
@@ -170,11 +170,11 @@ class UnloadController : public content::NotificationObserver,
   class DetachedWebContentsDelegate;
   scoped_ptr<DetachedWebContentsDelegate> detached_delegate_;
 
-  base::WeakPtrFactory<UnloadController> weak_factory_;
+  base::WeakPtrFactory<FastUnloadController> weak_factory_;
 
-  DISALLOW_COPY_AND_ASSIGN(UnloadController);
+  DISALLOW_COPY_AND_ASSIGN(FastUnloadController);
 };
 
 }  // namespace chrome
 
-#endif  // CHROME_BROWSER_UI_UNLOAD_CONTROLLER_H_
+#endif  // CHROME_BROWSER_UI_FAST_UNLOAD_CONTROLLER_H_