Upstream Chrome on iOS source code [2/11].

ios/chrome/browser/tabs/tab_loading_delegate.h

+// Copyright 2013 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 IOS_CHROME_BROWSER_TABS_TAB_LOADING_DELEGATE_H_
+#define IOS_CHROME_BROWSER_TABS_TAB_LOADING_DELEGATE_H_
+
+#import <UIKit/UIKit.h>
+
+// A protocol implemented by a delegate managing Tab loading. This protocol
+// is used by a Tab that's being preloaded before being displayed to inform the
+// entity that's preloading it that it should take some action. In the
+// QuickBack system, for example, a QuickBackLoadController will start loading
+// a Tab for a search link, and hold it in this loading state until it's
+// ready to display. The QuickBackLoadController is then set as this Tab's
+// TabLoadingDelegate, which allows the Tab to let its owning controller know
+// if it needs to be cancelled or displayed.
+@protocol TabLoadingDelegate
+// Display the preloading tab immediately.
+- (void)displayPreloadingLinkImmediately;
+// Cancel preloading tab.
+- (void)cancelPreloadingTab;
+// Informs the delegate that the tab aborted load internally (e.g., due to
+// launching an external URL), so the preloading should be abandoned and the
+// source tab restored to its pre-load-attempt state.
+- (void)preloadingTabAborted;
+
+@end
+
+#endif  // IOS_CHROME_BROWSER_TABS_TAB_LOADING_DELEGATE_H_