Add header for the Content Suggestions

ios/chrome/browser/ui/content_suggestions/content_suggestions_footer_item.mm

 // Copyright 2017 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.
 
 #import "ios/chrome/browser/ui/content_suggestions/content_suggestions_footer_item.h"
 
 #import "ios/chrome/browser/ui/uikit_ui_util.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 namespace {
 const CGFloat kMinimalCellHeight = 44;
 }
 
 #pragma mark - ContentSuggestionsFooterItem
 
 @interface ContentSuggestionsFooterItem ()
 
 @property(nonatomic, copy) NSString* title;
 @property(nonatomic, copy) ProceduralBlock block;
 
 @end
 
 @implementation ContentSuggestionsFooterItem
 
 @synthesize title = _title;
 @synthesize block = _block;
-@synthesize suggestionIdentifier = _suggestionIdentifier;
 
 - (instancetype)initWithType:(NSInteger)type
                        title:(NSString*)title
                        block:(ProceduralBlock)block {
   self = [super initWithType:type];
   if (self) {
     self.cellClass = [ContentSuggestionsFooterCell class];
     _title = [title copy];
     _block = [block copy];
   }
@@ skipping 39 matching lines @@
   return self;
 }
 
 - (void)prepareForReuse {
   [self.button removeTarget:nil
                      action:NULL
            forControlEvents:UIControlEventAllEvents];
 }
 
 @end