Reland of [ObjC ARC] Converts ios/chrome/browser/ui/contextual_search:contextual_search to ARC.

ios/chrome/browser/ui/contextual_search/contextual_search_results_view.h

 // Copyright 2016 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_UI_CONTEXTUAL_SEARCH_CONTEXTUAL_SEARCH_RESULTS_VIEW_H_
 #define IOS_CHROME_BROWSER_UI_CONTEXTUAL_SEARCH_CONTEXTUAL_SEARCH_RESULTS_VIEW_H_
 
 #import <UIKit/UIKit.h>
 
 #import "ios/chrome/browser/ui/contextual_search/contextual_search_controller.h"
@@ skipping 14 matching lines @@
 // YES if it's OK to preload search results.
 - (BOOL)canPreloadSearchResults;
 @end
 
 @interface ContextualSearchResultsView
     : UIView<ContextualSearchPanelMotionObserver,
              ContextualSearchPanelScrollSynchronizer,
              ContextualSearchTabProvider>
 @property(nonatomic, assign) BOOL active;
 // The tab that is credited with opening the search results tab.
-@property(nonatomic, assign) Tab* opener;
+@property(nonatomic, weak) Tab* opener;
 // Object that can handle promoting the search results.
-@property(nonatomic, assign) id<ContextualSearchTabPromoter> promoter;
+@property(nonatomic, weak) id<ContextualSearchTabPromoter> promoter;
 // Object that can determine if search results can be preloaded.
-@property(nonatomic, assign) id<ContextualSearchPreloadChecker> preloadChecker;
+@property(nonatomic, weak) id<ContextualSearchPreloadChecker> preloadChecker;
 // YES if the search results have loaded and this view was visible.
 @property(nonatomic, readonly) BOOL contentVisible;
 
 // Creates an new (internal) Tab object loading |url|; if |preloadEnabled| is
 // YES, then this tab will start loading as soon as possible, otherwise it will
 // start loading as soon as this view becomes visible.
 - (void)createTabForSearch:(GURL)url preloadEnabled:(BOOL)preloadEnabled;
 
 // Scroll the search results tab content so the top of the loaded page is
 // visible.
 - (void)scrollToTopAnimated:(BOOL)animated;
 
 // Record metrics for the loaded search results having finished, marking them
 // as 'chained' or not according to |chained|.
 - (void)recordFinishedSearchChained:(BOOL)chained;
 
 @end
 
 #endif  // IOS_CHROME_BROWSER_UI_CONTEXTUAL_SEARCH_CONTEXTUAL_SEARCH_RESULTS_VIEW_H_